diff --git a/engine/src/androidTest/java/com/google/android/fhir/db/impl/DatabaseImplTest.kt b/engine/src/androidTest/java/com/google/android/fhir/db/impl/DatabaseImplTest.kt
index f8544be53f..2dd7651e25 100644
--- a/engine/src/androidTest/java/com/google/android/fhir/db/impl/DatabaseImplTest.kt
+++ b/engine/src/androidTest/java/com/google/android/fhir/db/impl/DatabaseImplTest.kt
@@ -19,10 +19,12 @@ package com.google.android.fhir.db.impl
 import android.content.Context
 import androidx.test.core.app.ApplicationProvider
 import androidx.test.filters.MediumTest
+import ca.uhn.fhir.rest.gclient.StringClientParam
 import ca.uhn.fhir.rest.param.ParamPrefixEnum
 import com.google.android.fhir.DateProvider
 import com.google.android.fhir.FhirServices
 import com.google.android.fhir.LocalChange
+import com.google.android.fhir.db.Database
 import com.google.android.fhir.db.ResourceNotFoundException
 import com.google.android.fhir.db.impl.dao.toLocalChange
 import com.google.android.fhir.db.impl.entities.LocalChangeEntity
@@ -50,7 +52,9 @@ import org.hl7.fhir.r4.model.DateTimeType
 import org.hl7.fhir.r4.model.DateType
 import org.hl7.fhir.r4.model.DecimalType
 import org.hl7.fhir.r4.model.Enumerations
+import org.hl7.fhir.r4.model.Extension
 import org.hl7.fhir.r4.model.HumanName
+import org.hl7.fhir.r4.model.Identifier
 import org.hl7.fhir.r4.model.Immunization
 import org.hl7.fhir.r4.model.Meta
 import org.hl7.fhir.r4.model.Observation
@@ -60,6 +64,8 @@ import org.hl7.fhir.r4.model.Quantity
 import org.hl7.fhir.r4.model.Reference
 import org.hl7.fhir.r4.model.ResourceType
 import org.hl7.fhir.r4.model.RiskAssessment
+import org.hl7.fhir.r4.model.SearchParameter
+import org.hl7.fhir.r4.model.StringType
 import org.json.JSONArray
 import org.junit.After
 import org.junit.Assert.assertThrows
@@ -84,15 +90,28 @@ class DatabaseImplTest {
   @JvmField @Parameterized.Parameter(0) var encrypted: Boolean = false
 
   private val context: Context = ApplicationProvider.getApplicationContext()
-  private val services =
-    FhirServices.builder(context)
-      .inMemory()
-      .apply { if (encrypted) enableEncryptionIfSupported() }
-      .build()
-  private val testingUtils = TestingUtils(services.parser)
-  private val database = services.database
-
-  @Before fun setUp(): Unit = runBlocking { database.insert(TEST_PATIENT_1) }
+  private lateinit var services: FhirServices
+  private lateinit var testingUtils: TestingUtils
+  private lateinit var database: Database
+
+  @Before
+  fun setUp(): Unit = runBlocking {
+    buildFhirService()
+    database.insert(TEST_PATIENT_1)
+  }
+
+  private fun buildFhirService(customSearchParameter: List<SearchParameter>? = null) {
+    services =
+      FhirServices.builder(context)
+        .inMemory()
+        .apply {
+          if (encrypted) enableEncryptionIfSupported()
+          setSearchParameters(customSearchParameter)
+        }
+        .build()
+    database = services.database
+    testingUtils = TestingUtils(services.parser)
+  }
 
   @After
   fun tearDown() {
@@ -451,10 +470,13 @@ class DatabaseImplTest {
   fun delete_nonExistent_shouldNotInsertLocalChange() = runBlocking {
     database.delete(ResourceType.Patient, "nonexistent_patient")
     assertThat(
-        database.getAllLocalChanges().map { it }.none {
-          it.localChange.type.equals(LocalChangeEntity.Type.DELETE) &&
-            it.localChange.resourceId.equals("nonexistent_patient")
-        }
+        database
+          .getAllLocalChanges()
+          .map { it }
+          .none {
+            it.localChange.type.equals(LocalChangeEntity.Type.DELETE) &&
+              it.localChange.resourceId.equals("nonexistent_patient")
+          }
       )
       .isTrue()
   }
@@ -480,9 +502,10 @@ class DatabaseImplTest {
     val patient: Patient = testingUtils.readFromFile(Patient::class.java, "/date_test_patient.json")
     database.insertRemote(patient)
     assertThat(
-        database.getAllLocalChanges().map { it }.none {
-          it.localChange.resourceId.equals(patient.logicalId)
-        }
+        database
+          .getAllLocalChanges()
+          .map { it }
+          .none { it.localChange.resourceId.equals(patient.logicalId) }
       )
       .isTrue()
   }
@@ -532,15 +555,17 @@ class DatabaseImplTest {
       }
     database.insert(patient)
     services.fhirEngine.syncUpload { it ->
-      it.first { it.resourceId == "remote-patient-3" }.let {
-        flowOf(
-          it.token to
-            Patient().apply {
-              id = it.resourceId
-              meta = remoteMeta
-            }
-        )
-      }
+      it
+        .first { it.resourceId == "remote-patient-3" }
+        .let {
+          flowOf(
+            it.token to
+              Patient().apply {
+                id = it.resourceId
+                meta = remoteMeta
+              }
+          )
+        }
     }
     val selectedEntity = database.selectEntity(ResourceType.Patient, "remote-patient-3")
     assertThat(selectedEntity.versionId).isEqualTo(remoteMeta.versionId)
@@ -552,9 +577,10 @@ class DatabaseImplTest {
     val patient: Patient = testingUtils.readFromFile(Patient::class.java, "/date_test_patient.json")
     database.insertRemote(patient, TEST_PATIENT_2)
     assertThat(
-        database.getAllLocalChanges().map { it }.none {
-          it.localChange.resourceId in listOf(patient.logicalId, TEST_PATIENT_2_ID)
-        }
+        database
+          .getAllLocalChanges()
+          .map { it }
+          .none { it.localChange.resourceId in listOf(patient.logicalId, TEST_PATIENT_2_ID) }
       )
       .isTrue()
   }
@@ -2547,7 +2573,8 @@ class DatabaseImplTest {
     )
 
     assertThat(
-        database.search<Patient>(
+        database
+          .search<Patient>(
             Search(ResourceType.Patient)
               .apply { sort(Patient.BIRTHDATE, Order.DESCENDING) }
               .getQuery()
@@ -2574,7 +2601,8 @@ class DatabaseImplTest {
     )
 
     assertThat(
-        database.search<Patient>(
+        database
+          .search<Patient>(
             Search(ResourceType.Patient)
               .apply { sort(Patient.BIRTHDATE, Order.ASCENDING) }
               .getQuery()
@@ -2832,6 +2860,129 @@ class DatabaseImplTest {
       .inOrder()
   }
 
+  @Test
+  fun search_patient_with_extension_as_search_param() = runBlocking {
+    val maidenNameSearchParameter =
+      SearchParameter().apply {
+        url = "http://example.com/SearchParameter/patient-mothersMaidenName"
+        addBase("Patient")
+        name = "mothers-maiden-name"
+        code = "mothers-maiden-name"
+        type = Enumerations.SearchParamType.STRING
+        expression =
+          "Patient.extension('http://hl7.org/fhir/StructureDefinition/patient-mothersMaidenName').value.as(String)"
+        description = "search on mother's maiden name"
+      }
+    val patient =
+      Patient().apply {
+        addIdentifier(
+          Identifier().apply {
+            system = "https://custom-identifier-namespace"
+            value = "OfficialIdentifier_DarcySmith_0001"
+          }
+        )
+
+        addName(
+          HumanName().apply {
+            use = HumanName.NameUse.OFFICIAL
+            family = "Smith"
+            addGiven("Darcy")
+            gender = Enumerations.AdministrativeGender.FEMALE
+            birthDateElement = DateType("1970-01-01")
+          }
+        )
+
+        addExtension(
+          Extension().apply {
+            url = "http://hl7.org/fhir/StructureDefinition/patient-mothersMaidenName"
+            setValue(StringType("Marca"))
+          }
+        )
+      }
+    // Get rid of the default service and create one with search params
+    tearDown()
+    buildFhirService(listOf(maidenNameSearchParameter))
+    database.insert(patient)
+
+    val result =
+      database.search<Patient>(
+        Search(ResourceType.Patient)
+          .apply {
+            filter(
+              StringClientParam("mothers-maiden-name"),
+              {
+                value = "Marca"
+                modifier = StringFilterModifier.MATCHES_EXACTLY
+              }
+            )
+          }
+          .getQuery()
+      )
+
+    assertThat(result.map { it.nameFirstRep.nameAsSingleString }).contains("Darcy Smith")
+  }
+
+  @Test
+  fun search_patient_with_custom_value_as_search_param() = runBlocking {
+    val patient =
+      Patient().apply {
+        addIdentifier(
+          Identifier().apply {
+            system = "https://custom-identifier-namespace"
+            value = "OfficialIdentifier_DarcySmith_0001"
+          }
+        )
+
+        addName(
+          HumanName().apply {
+            use = HumanName.NameUse.OFFICIAL
+            family = "Smith"
+            addGiven("Darcy")
+            gender = Enumerations.AdministrativeGender.FEMALE
+            birthDateElement = DateType("1970-01-01")
+          }
+        )
+
+        addExtension(
+          Extension().apply {
+            url = "http://hl7.org/fhir/StructureDefinition/patient-mothersMaidenName"
+            setValue(StringType("Marca"))
+          }
+        )
+      }
+    val identifierPartialSearchParameter =
+      SearchParameter().apply {
+        url = "http://example.com/SearchParameter/patient-identifierPartial"
+        addBase("Patient")
+        name = "identifierPartial"
+        code = "identifierPartial"
+        type = Enumerations.SearchParamType.STRING
+        expression = "Patient.identifier.value"
+        description = "Search the identifier"
+      }
+    // Get rid of the default service and create one with search params
+    tearDown()
+    buildFhirService(listOf(identifierPartialSearchParameter))
+    database.insert(patient)
+
+    val result =
+      database.search<Patient>(
+        Search(ResourceType.Patient)
+          .apply {
+            filter(
+              StringClientParam("identifierPartial"),
+              {
+                value = "OfficialIdentifier_"
+                modifier = StringFilterModifier.STARTS_WITH
+              }
+            )
+          }
+          .getQuery()
+      )
+
+    assertThat(result.map { it.nameFirstRep.nameAsSingleString }).contains("Darcy Smith")
+  }
+
   private companion object {
     const val mockEpochTimeStamp = 1628516301000
     const val TEST_PATIENT_1_ID = "test_patient_1"
diff --git a/engine/src/androidTest/java/com/google/android/fhir/db/impl/EncryptedDatabaseErrorTest.kt b/engine/src/androidTest/java/com/google/android/fhir/db/impl/EncryptedDatabaseErrorTest.kt
index 1cfeeea9dd..eb52f8db26 100644
--- a/engine/src/androidTest/java/com/google/android/fhir/db/impl/EncryptedDatabaseErrorTest.kt
+++ b/engine/src/androidTest/java/com/google/android/fhir/db/impl/EncryptedDatabaseErrorTest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Google LLC
+ * Copyright 2022 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,8 @@ import com.google.android.fhir.DatabaseErrorStrategy.UNSPECIFIED
 import com.google.android.fhir.db.impl.DatabaseImpl.Companion.DATABASE_PASSPHRASE_NAME
 import com.google.android.fhir.db.impl.DatabaseImpl.Companion.ENCRYPTED_DATABASE_NAME
 import com.google.android.fhir.db.impl.DatabaseImpl.Companion.UNENCRYPTED_DATABASE_NAME
+import com.google.android.fhir.index.ResourceIndexer
+import com.google.android.fhir.index.SearchParamDefinitionsProviderImpl
 import com.google.android.fhir.search.Order
 import com.google.android.fhir.search.Search
 import com.google.android.fhir.search.getQuery
@@ -46,6 +48,7 @@ import org.junit.runner.RunWith
 class EncryptedDatabaseErrorTest {
   private val context: Context = ApplicationProvider.getApplicationContext()
   private val parser = FhirContext.forR4().newJsonParser()
+  private val resourceIndexer = ResourceIndexer(SearchParamDefinitionsProviderImpl())
 
   @After
   fun tearDown() {
@@ -65,7 +68,8 @@ class EncryptedDatabaseErrorTest {
               inMemory = false,
               enableEncryption = false,
               databaseErrorStrategy = UNSPECIFIED
-            )
+            ),
+            resourceIndexer
           )
           .let {
             it.insert(TEST_PATIENT_1)
@@ -81,7 +85,8 @@ class EncryptedDatabaseErrorTest {
               inMemory = false,
               enableEncryption = true,
               databaseErrorStrategy = UNSPECIFIED
-            )
+            ),
+            resourceIndexer
           )
           .let {
             it.search<Patient>(
@@ -110,7 +115,8 @@ class EncryptedDatabaseErrorTest {
               inMemory = false,
               enableEncryption = true,
               databaseErrorStrategy = UNSPECIFIED
-            )
+            ),
+            resourceIndexer
           )
           .let {
             it.insert(TEST_PATIENT_1)
@@ -132,7 +138,8 @@ class EncryptedDatabaseErrorTest {
               inMemory = false,
               enableEncryption = true,
               databaseErrorStrategy = UNSPECIFIED
-            )
+            ),
+            resourceIndexer
           )
           .let {
             it.search<Patient>(
@@ -160,7 +167,8 @@ class EncryptedDatabaseErrorTest {
             inMemory = false,
             enableEncryption = true,
             databaseErrorStrategy = UNSPECIFIED
-          )
+          ),
+          resourceIndexer
         )
         .let {
           it.insert(TEST_PATIENT_1)
@@ -182,7 +190,8 @@ class EncryptedDatabaseErrorTest {
             inMemory = false,
             enableEncryption = true,
             databaseErrorStrategy = RECREATE_AT_OPEN
-          )
+          ),
+          resourceIndexer
         )
         .let {
           assertThat(
@@ -213,7 +222,8 @@ class EncryptedDatabaseErrorTest {
               inMemory = false,
               enableEncryption = true,
               databaseErrorStrategy = UNSPECIFIED
-            )
+            ),
+            resourceIndexer
           )
           .let {
             it.insert(TEST_PATIENT_1)
@@ -229,7 +239,8 @@ class EncryptedDatabaseErrorTest {
               inMemory = false,
               enableEncryption = false,
               databaseErrorStrategy = UNSPECIFIED
-            )
+            ),
+            resourceIndexer
           )
           .let {
             assertThat(
diff --git a/engine/src/main/java/com/google/android/fhir/FhirEngineProvider.kt b/engine/src/main/java/com/google/android/fhir/FhirEngineProvider.kt
index 2269d31266..5e657cbf80 100644
--- a/engine/src/main/java/com/google/android/fhir/FhirEngineProvider.kt
+++ b/engine/src/main/java/com/google/android/fhir/FhirEngineProvider.kt
@@ -21,6 +21,7 @@ import com.google.android.fhir.DatabaseErrorStrategy.UNSPECIFIED
 import com.google.android.fhir.sync.Authenticator
 import com.google.android.fhir.sync.DataSource
 import com.google.android.fhir.sync.remote.HttpLogger
+import org.hl7.fhir.r4.model.SearchParameter
 
 /** The provider for [FhirEngine] instance. */
 object FhirEngineProvider {
@@ -68,6 +69,7 @@ object FhirEngineProvider {
             if (configuration.enableEncryptionIfSupported) enableEncryptionIfSupported()
             setDatabaseErrorStrategy(configuration.databaseErrorStrategy)
             configuration.serverConfiguration?.let { setServerConfiguration(it) }
+            configuration.customSearchParameters?.let { setSearchParameters(it) }
             if (configuration.testMode) {
               inMemory()
             }
@@ -105,7 +107,20 @@ data class FhirEngineConfiguration(
   val enableEncryptionIfSupported: Boolean = false,
   val databaseErrorStrategy: DatabaseErrorStrategy = UNSPECIFIED,
   val serverConfiguration: ServerConfiguration? = null,
-  val testMode: Boolean = false
+  val testMode: Boolean = false,
+  /**
+   * Additional search parameters to be used to query FHIR engine using the search API. These are in
+   * addition to the default search parameters defined in
+   * [FHIR](https://www.hl7.org/fhir/searchparameter-registry.html). The search parameters should be
+   * unique and not change the existing/default search parameters and it may lead to unexpected
+   * search behaviour.
+   *
+   * NOTE: The engine doesn't reindex resources after a new [SearchParameter] is added to the
+   * engine. It is the responsibility of the app developer to reindex the resources by updating
+   * them. Any new CRUD operations on a resource after a new [SearchParameter] is added will result
+   * in the reindexing of the resource.
+   */
+  val customSearchParameters: List<SearchParameter>? = null
 )
 
 enum class DatabaseErrorStrategy {
diff --git a/engine/src/main/java/com/google/android/fhir/FhirServices.kt b/engine/src/main/java/com/google/android/fhir/FhirServices.kt
index c81afdc6d5..eb11475d81 100644
--- a/engine/src/main/java/com/google/android/fhir/FhirServices.kt
+++ b/engine/src/main/java/com/google/android/fhir/FhirServices.kt
@@ -25,8 +25,11 @@ import com.google.android.fhir.db.impl.DatabaseConfig
 import com.google.android.fhir.db.impl.DatabaseEncryptionKeyProvider.isDatabaseEncryptionSupported
 import com.google.android.fhir.db.impl.DatabaseImpl
 import com.google.android.fhir.impl.FhirEngineImpl
+import com.google.android.fhir.index.ResourceIndexer
+import com.google.android.fhir.index.SearchParamDefinitionsProviderImpl
 import com.google.android.fhir.sync.DataSource
 import com.google.android.fhir.sync.remote.RemoteFhirService
+import org.hl7.fhir.r4.model.SearchParameter
 import timber.log.Timber
 
 internal data class FhirServices(
@@ -40,6 +43,7 @@ internal data class FhirServices(
     private var enableEncryption: Boolean = false
     private var databaseErrorStrategy = DatabaseErrorStrategy.UNSPECIFIED
     private var serverConfiguration: ServerConfiguration? = null
+    private var searchParameters: List<SearchParameter>? = null
 
     internal fun inMemory() = apply { inMemory = true }
 
@@ -59,13 +63,20 @@ internal data class FhirServices(
       this.serverConfiguration = serverConfiguration
     }
 
+    internal fun setSearchParameters(searchParameters: List<SearchParameter>?) = apply {
+      this.searchParameters = searchParameters
+    }
+
     fun build(): FhirServices {
       val parser = FhirContext.forCached(FhirVersionEnum.R4).newJsonParser()
+      val searchParamMap =
+        searchParameters?.asMapOfResourceTypeToSearchParamDefinitions() ?: emptyMap()
       val db =
         DatabaseImpl(
           context = context,
           iParser = parser,
-          DatabaseConfig(inMemory, enableEncryption, databaseErrorStrategy)
+          DatabaseConfig(inMemory, enableEncryption, databaseErrorStrategy),
+          resourceIndexer = ResourceIndexer(SearchParamDefinitionsProviderImpl(searchParamMap))
         )
       val engine = FhirEngineImpl(database = db, context = context)
       val remoteDataSource =
@@ -79,7 +90,7 @@ internal data class FhirServices(
         fhirEngine = engine,
         parser = parser,
         database = db,
-        remoteDataSource = remoteDataSource
+        remoteDataSource = remoteDataSource,
       )
     }
   }
diff --git a/engine/src/main/java/com/google/android/fhir/MoreSearchParameters.kt b/engine/src/main/java/com/google/android/fhir/MoreSearchParameters.kt
new file mode 100644
index 0000000000..f180538e48
--- /dev/null
+++ b/engine/src/main/java/com/google/android/fhir/MoreSearchParameters.kt
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.fhir
+
+import com.google.android.fhir.index.SearchParamDefinition
+import org.hl7.fhir.r4.model.SearchParameter
+
+/**
+ * Converts a list of [SearchParameter]s into a Map of resourceType string and list of associated
+ * [SearchParamDefinition].
+ */
+internal fun List<SearchParameter>.asMapOfResourceTypeToSearchParamDefinitions():
+  Map<String, List<SearchParamDefinition>> =
+  flatMap { it.toSearchParamDefinition() }.groupBy({ it.first }, { it.second })
+
+/** @return List of pairs of resourceType string and associated [SearchParamDefinition]. */
+internal fun SearchParameter.toSearchParamDefinition(): List<Pair<String, SearchParamDefinition>> {
+  require(!name.isNullOrEmpty()) { "SearchParameter.name can't be null or empty." }
+
+  requireNotNull(type) { "SearchParameter.type can't be null." }
+
+  require(!expression.isNullOrEmpty()) { "SearchParameter.expression can't be null or empty." }
+
+  return getResourceToPathMap(this).map { (resourceType, path) ->
+    resourceType to SearchParamDefinition(name = name, type = type, path = path)
+  }
+}
+
+private fun getResourceToPathMap(searchParam: SearchParameter): Map<String, String> {
+  // the if block is added because of the issue https://jira.hl7.org/browse/FHIR-22724 and can
+  // be removed once the issue is resolved
+  return if (searchParam.base.size == 1) {
+    mapOf(searchParam.base.single().valueAsString to searchParam.expression)
+  } else {
+    searchParam.expression
+      .split("|")
+      .groupBy { splitString -> splitString.split(".").first().trim().removePrefix("(") }
+      .mapValues { it.value.joinToString(" | ") { join -> join.trim() } }
+  }
+}
diff --git a/engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt b/engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt
index 0be6124821..b075ff5104 100644
--- a/engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt
+++ b/engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt
@@ -31,9 +31,9 @@ import com.google.android.fhir.db.impl.dao.SquashedLocalChange
 import com.google.android.fhir.db.impl.entities.LocalChangeEntity
 import com.google.android.fhir.db.impl.entities.ResourceEntity
 import com.google.android.fhir.db.impl.entities.SyncedResourceEntity
+import com.google.android.fhir.index.ResourceIndexer
 import com.google.android.fhir.logicalId
 import com.google.android.fhir.search.SearchQuery
-import java.lang.IllegalStateException
 import java.time.Instant
 import org.hl7.fhir.r4.model.Resource
 import org.hl7.fhir.r4.model.ResourceType
@@ -46,7 +46,8 @@ import org.hl7.fhir.r4.model.ResourceType
 internal class DatabaseImpl(
   private val context: Context,
   private val iParser: IParser,
-  databaseConfig: DatabaseConfig
+  databaseConfig: DatabaseConfig,
+  private val resourceIndexer: ResourceIndexer
 ) : com.google.android.fhir.db.Database {
 
   val db: ResourceDatabase
@@ -96,7 +97,12 @@ internal class DatabaseImpl(
         .build()
   }
 
-  private val resourceDao by lazy { db.resourceDao().also { it.iParser = iParser } }
+  private val resourceDao by lazy {
+    db.resourceDao().also {
+      it.iParser = iParser
+      it.resourceIndexer = resourceIndexer
+    }
+  }
   private val syncedResourceDao = db.syncedResourceDao()
   private val localChangeDao = db.localChangeDao().also { it.iParser = iParser }
 
@@ -145,8 +151,7 @@ internal class DatabaseImpl(
         iParser.parseResource(it)
       }
         ?: throw ResourceNotFoundException(type.name, id)
-    } as
-      Resource
+    } as Resource
   }
 
   override suspend fun lastUpdate(resourceType: ResourceType): String? {
@@ -202,9 +207,12 @@ internal class DatabaseImpl(
    */
   override suspend fun getAllLocalChanges(): List<SquashedLocalChange> {
     return db.withTransaction {
-      localChangeDao.getAllLocalChanges().groupBy { it.resourceId to it.resourceType }.values.map {
-        SquashedLocalChange(LocalChangeToken(it.map { it.id }), LocalChangeUtils.squash(it))
-      }
+      localChangeDao
+        .getAllLocalChanges()
+        .groupBy { it.resourceId to it.resourceType }
+        .values.map {
+          SquashedLocalChange(LocalChangeToken(it.map { it.id }), LocalChangeUtils.squash(it))
+        }
     }
   }
 
diff --git a/engine/src/main/java/com/google/android/fhir/db/impl/dao/ResourceDao.kt b/engine/src/main/java/com/google/android/fhir/db/impl/dao/ResourceDao.kt
index 8633c6b1bc..96055acb05 100644
--- a/engine/src/main/java/com/google/android/fhir/db/impl/dao/ResourceDao.kt
+++ b/engine/src/main/java/com/google/android/fhir/db/impl/dao/ResourceDao.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Google LLC
+ * Copyright 2022 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,6 +49,7 @@ internal abstract class ResourceDao {
   // this is ugly but there is no way to inject these right now in Room as it is the one creating
   // the dao
   lateinit var iParser: IParser
+  lateinit var resourceIndexer: ResourceIndexer
 
   open suspend fun update(resource: Resource) {
     updateResource(
@@ -67,7 +68,7 @@ internal abstract class ResourceDao {
           versionId = it.versionId,
           lastUpdatedRemote = it.lastUpdatedRemote
         )
-      val index = ResourceIndexer.index(resource)
+      val index = resourceIndexer.index(resource)
       updateIndicesForResource(index, entity, it.resourceUuid)
     }
       ?: throw ResourceNotFoundException(resource.resourceType.name, resource.id)
@@ -191,7 +192,7 @@ internal abstract class ResourceDao {
         lastUpdatedRemote = resource.lastUpdated
       )
     insertResource(entity)
-    val index = ResourceIndexer.index(resource)
+    val index = resourceIndexer.index(resource)
     updateIndicesForResource(index, entity, resourceUuid)
 
     return resource.id
diff --git a/engine/src/main/java/com/google/android/fhir/index/ResourceIndexer.kt b/engine/src/main/java/com/google/android/fhir/index/ResourceIndexer.kt
index 9ea8560caf..46b0277601 100644
--- a/engine/src/main/java/com/google/android/fhir/index/ResourceIndexer.kt
+++ b/engine/src/main/java/com/google/android/fhir/index/ResourceIndexer.kt
@@ -63,7 +63,9 @@ import org.hl7.fhir.r4.utils.FHIRPathEngine
  * Indexes a FHIR resource according to the
  * [search parameters](https://www.hl7.org/fhir/searchparameter-registry.html).
  */
-internal object ResourceIndexer {
+internal class ResourceIndexer(
+  private val searchParamDefinitionsProvider: SearchParamDefinitionsProvider
+) {
   // Switched HapiWorkerContext to SimpleWorkerContext as a fix for
   // https://github.com/google/android-fhir/issues/768
   private val fhirPathEngine = FHIRPathEngine(SimpleWorkerContext())
@@ -72,7 +74,8 @@ internal object ResourceIndexer {
 
   private fun <R : Resource> extractIndexValues(resource: R): ResourceIndices {
     val indexBuilder = ResourceIndices.Builder(resource.resourceType, resource.logicalId)
-    getSearchParamList(resource)
+    searchParamDefinitionsProvider
+      .get(resource)
       .map { it to fhirPathEngine.evaluate(resource, it.path) }
       .flatMap { pair -> pair.second.map { pair.first to it } }
       .forEach { pair ->
@@ -400,11 +403,13 @@ internal object ResourceIndexer {
     }
   }
 
-  /**
-   * The FHIR currency code system. See: https://bit.ly/30YB3ML. See:
-   * https://www.hl7.org/fhir/valueset-currencies.html.
-   */
-  private const val FHIR_CURRENCY_CODE_SYSTEM = "urn:iso:std:iso:4217"
+  companion object {
+    /**
+     * The FHIR currency code system. See: https://bit.ly/30YB3ML. See:
+     * https://www.hl7.org/fhir/valueset-currencies.html.
+     */
+    private const val FHIR_CURRENCY_CODE_SYSTEM = "urn:iso:std:iso:4217"
+  }
 }
 
 data class SearchParamDefinition(val name: String, val type: SearchParamType, val path: String)
diff --git a/engine/src/main/java/com/google/android/fhir/index/SearchParamDefinitionsProvider.kt b/engine/src/main/java/com/google/android/fhir/index/SearchParamDefinitionsProvider.kt
new file mode 100644
index 0000000000..f8ed84ef64
--- /dev/null
+++ b/engine/src/main/java/com/google/android/fhir/index/SearchParamDefinitionsProvider.kt
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.fhir.index
+
+import org.hl7.fhir.r4.model.Resource
+
+/** Provides a list of [SearchParamDefinition]s for a [Resource]. */
+internal fun interface SearchParamDefinitionsProvider {
+
+  /** @return [SearchParamDefinition]s based on the [Resource.fhirType]. */
+  fun get(resource: Resource): List<SearchParamDefinition>
+}
+
+/**
+ * An implementation of [SearchParamDefinitionsProvider] that provides the [List]<
+ * [SearchParamDefinition]> from the default params and custom params(if any).
+ */
+internal class SearchParamDefinitionsProviderImpl(
+  private val customParams: Map<String, List<SearchParamDefinition>> = emptyMap()
+) : SearchParamDefinitionsProvider {
+
+  override fun get(resource: Resource): List<SearchParamDefinition> {
+    return getSearchParamList(resource) +
+      customParams.getOrDefault(resource.fhirType(), emptyList())
+  }
+}
diff --git a/engine/src/test/java/com/google/android/fhir/MoreSearchParametersTest.kt b/engine/src/test/java/com/google/android/fhir/MoreSearchParametersTest.kt
new file mode 100644
index 0000000000..bd6395fa8a
--- /dev/null
+++ b/engine/src/test/java/com/google/android/fhir/MoreSearchParametersTest.kt
@@ -0,0 +1,225 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.android.fhir
+
+import com.google.android.fhir.index.SearchParamDefinition
+import com.google.common.truth.Truth.assertThat
+import org.hl7.fhir.r4.model.Enumerations
+import org.hl7.fhir.r4.model.SearchParameter
+import org.junit.Assert.assertThrows
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+@RunWith(RobolectricTestRunner::class)
+class MoreSearchParametersTest {
+  @Test
+  fun asMapOfResourceTypeToSearchParamDefinitions() {
+
+    val familyNameSearchParameter =
+      SearchParameter().apply {
+        name = "family"
+        expression = "Patient.name.family | Practitioner.name.family"
+        addBase("Patient")
+        addBase("Practitioner")
+        type = Enumerations.SearchParamType.STRING
+      }
+
+    val genderSearchParameter =
+      SearchParameter().apply {
+        name = "gender"
+        expression = "Patient.gender | Person.gender | Practitioner.gender | RelatedPerson.gender"
+        addBase("Patient")
+        addBase("Person")
+        addBase("Practitioner")
+        addBase("RelatedPerson")
+        type = Enumerations.SearchParamType.TOKEN
+      }
+
+    val result =
+      listOf(familyNameSearchParameter, genderSearchParameter)
+        .asMapOfResourceTypeToSearchParamDefinitions()
+
+    assertThat(result)
+      .containsEntry(
+        "Patient",
+        listOf(
+          SearchParamDefinition(
+            name = "family",
+            type = Enumerations.SearchParamType.STRING,
+            path = "Patient.name.family"
+          ),
+          SearchParamDefinition(
+            name = "gender",
+            type = Enumerations.SearchParamType.TOKEN,
+            path = "Patient.gender"
+          )
+        )
+      )
+    assertThat(result)
+      .containsEntry(
+        "Practitioner",
+        listOf(
+          SearchParamDefinition(
+            name = "family",
+            type = Enumerations.SearchParamType.STRING,
+            path = "Practitioner.name.family"
+          ),
+          SearchParamDefinition(
+            name = "gender",
+            type = Enumerations.SearchParamType.TOKEN,
+            path = "Practitioner.gender"
+          )
+        )
+      )
+    assertThat(result)
+      .containsEntry(
+        "Person",
+        listOf(
+          SearchParamDefinition(
+            name = "gender",
+            type = Enumerations.SearchParamType.TOKEN,
+            path = "Person.gender"
+          )
+        )
+      )
+    assertThat(result)
+      .containsEntry(
+        "RelatedPerson",
+        listOf(
+          SearchParamDefinition(
+            name = "gender",
+            type = Enumerations.SearchParamType.TOKEN,
+            path = "RelatedPerson.gender"
+          )
+        )
+      )
+  }
+
+  @Test
+  fun toSearchParamDefinition() {
+    val familySearchParameter =
+      SearchParameter().apply {
+        name = "family"
+        expression = "Patient.name.family | Practitioner.name.family"
+        addBase("Patient")
+        addBase("Practitioner")
+        type = Enumerations.SearchParamType.STRING
+      }
+
+    val result = familySearchParameter.toSearchParamDefinition()
+    assertThat(result)
+      .containsExactly(
+        "Patient" to
+          SearchParamDefinition(
+            name = "family",
+            type = Enumerations.SearchParamType.STRING,
+            path = "Patient.name.family"
+          ),
+        "Practitioner" to
+          SearchParamDefinition(
+            name = "family",
+            type = Enumerations.SearchParamType.STRING,
+            path = "Practitioner.name.family"
+          )
+      )
+  }
+
+  @Test
+  fun toSearchParamDefinition_throws_IllegalArgumentException_when_name_is_null_or_empty() {
+    val nullNameSearchParameter =
+      SearchParameter().apply {
+        name = null
+        expression = "Patient.name.family | Practitioner.name.family"
+        addBase("Patient")
+        addBase("Practitioner")
+        type = Enumerations.SearchParamType.STRING
+      }
+
+    var exception =
+      assertThrows(null, IllegalArgumentException::class.java) {
+        nullNameSearchParameter.toSearchParamDefinition()
+      }
+    assertThat(exception.message).isEqualTo("SearchParameter.name can't be null or empty.")
+
+    val emptyNameSearchParameter =
+      SearchParameter().apply {
+        name = ""
+        expression = "Patient.name.family | Practitioner.name.family"
+        addBase("Patient")
+        addBase("Practitioner")
+        type = Enumerations.SearchParamType.STRING
+      }
+
+    exception =
+      assertThrows(null, IllegalArgumentException::class.java) {
+        emptyNameSearchParameter.toSearchParamDefinition()
+      }
+    assertThat(exception.message).isEqualTo("SearchParameter.name can't be null or empty.")
+  }
+
+  @Test
+  fun toSearchParamDefinition_throws_IllegalArgumentException_when_expression_is_null_or_empty() {
+    val nullExpressionSearchParameter =
+      SearchParameter().apply {
+        name = "family"
+        expression = null
+        addBase("Patient")
+        addBase("Practitioner")
+        type = Enumerations.SearchParamType.STRING
+      }
+
+    var exception =
+      assertThrows(null, IllegalArgumentException::class.java) {
+        nullExpressionSearchParameter.toSearchParamDefinition()
+      }
+    assertThat(exception.message).isEqualTo("SearchParameter.expression can't be null or empty.")
+
+    val emptyExpressionSearchParameter =
+      SearchParameter().apply {
+        name = "family"
+        expression = ""
+        addBase("Patient")
+        addBase("Practitioner")
+        type = Enumerations.SearchParamType.STRING
+      }
+
+    exception =
+      assertThrows(null, IllegalArgumentException::class.java) {
+        emptyExpressionSearchParameter.toSearchParamDefinition()
+      }
+    assertThat(exception.message).isEqualTo("SearchParameter.expression can't be null or empty.")
+  }
+
+  @Test
+  fun toSearchParamDefinition_throws_IllegalArgumentException_when_type_is_null() {
+    val nullTypeSearchParameter =
+      SearchParameter().apply {
+        name = "family"
+        expression = "Patient.name.family | Practitioner.name.family"
+        addBase("Patient")
+        addBase("Practitioner")
+        type = null
+      }
+
+    val exception =
+      assertThrows(null, IllegalArgumentException::class.java) {
+        nullTypeSearchParameter.toSearchParamDefinition()
+      }
+    assertThat(exception.message).isEqualTo("SearchParameter.type can't be null.")
+  }
+}
diff --git a/engine/src/test/java/com/google/android/fhir/index/ResourceIndexerTest.kt b/engine/src/test/java/com/google/android/fhir/index/ResourceIndexerTest.kt
index c1b8fdfde9..1b41962b67 100644
--- a/engine/src/test/java/com/google/android/fhir/index/ResourceIndexerTest.kt
+++ b/engine/src/test/java/com/google/android/fhir/index/ResourceIndexerTest.kt
@@ -45,6 +45,7 @@ import org.hl7.fhir.r4.model.DecimalType
 import org.hl7.fhir.r4.model.Device
 import org.hl7.fhir.r4.model.Encounter
 import org.hl7.fhir.r4.model.Enumerations
+import org.hl7.fhir.r4.model.Extension
 import org.hl7.fhir.r4.model.HumanName
 import org.hl7.fhir.r4.model.Identifier
 import org.hl7.fhir.r4.model.InstantType
@@ -76,11 +77,13 @@ import org.robolectric.annotation.Config
 @Config(sdk = [Build.VERSION_CODES.P])
 class ResourceIndexerTest {
 
+  private val resourceIndexer = ResourceIndexer(SearchParamDefinitionsProviderImpl())
+
   /** Unit tests for resource indexer */
   @Test
   fun index_id() {
     val patient = Patient().apply { id = "3f511720-43c4-451a-830b-7f4817c619fb" }
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.tokenIndices)
       .contains(TokenIndex("_id", "Patient.id", null, "3f511720-43c4-451a-830b-7f4817c619fb"))
   }
@@ -93,7 +96,7 @@ class ResourceIndexerTest {
         meta = Meta().setLastUpdated(InstantType("2001-09-01T23:09:09.000+05:30").value)
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.dateTimeIndices)
       .contains(
@@ -113,7 +116,7 @@ class ResourceIndexerTest {
         id = "non-null-ID"
         meta = Meta().setProfile(mutableListOf(CanonicalType("Profile/lipid")))
       }
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.referenceIndices)
       .contains(ReferenceIndex("_profile", "Patient.meta.profile", "Profile/lipid"))
   }
@@ -125,7 +128,7 @@ class ResourceIndexerTest {
         id = "non-null-ID"
         meta = Meta().setProfile(mutableListOf(CanonicalType("")))
       }
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.referenceIndices.any { it.name == "_profile" }).isFalse()
   }
 
@@ -138,7 +141,7 @@ class ResourceIndexerTest {
         id = "non-null-ID"
         meta = Meta().setTag(mutableListOf(Coding(systemString, codeString, "display")))
       }
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.tokenIndices)
       .contains(TokenIndex("_tag", "Patient.meta.tag", systemString, codeString))
@@ -151,7 +154,7 @@ class ResourceIndexerTest {
         id = "non-null-ID"
         meta = Meta().setTag(mutableListOf(Coding("", "", "")))
       }
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.tokenIndices.any { it.name == "_tag" }).isFalse()
   }
@@ -165,7 +168,7 @@ class ResourceIndexerTest {
         referenceSeq.windowStart = value
       }
 
-    val resourceIndices = ResourceIndexer.index(molecularSequence)
+    val resourceIndices = resourceIndexer.index(molecularSequence)
 
     assertThat(resourceIndices.numberIndices)
       .contains(
@@ -189,7 +192,7 @@ class ResourceIndexerTest {
           )
       }
 
-    val resourceIndices = ResourceIndexer.index(riskAssessment)
+    val resourceIndices = resourceIndexer.index(riskAssessment)
 
     assertThat(resourceIndices.numberIndices)
       .contains(NumberIndex("probability", "RiskAssessment.prediction.probability", value))
@@ -204,7 +207,7 @@ class ResourceIndexerTest {
         referenceSeq = value
       }
 
-    val resourceIndices = ResourceIndexer.index(molecularSequence)
+    val resourceIndices = resourceIndexer.index(molecularSequence)
 
     assertThat(resourceIndices.numberIndices.any { it.name == "window-start" }).isFalse()
     assertThat(
@@ -223,7 +226,7 @@ class ResourceIndexerTest {
         birthDate = date.value
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.dateIndices)
       .contains(
@@ -243,7 +246,7 @@ class ResourceIndexerTest {
         id = "non-null-id"
         birthDate = null
       }
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.dateIndices.any { it.name == "birthdate" }).isFalse()
     assertThat(resourceIndices.dateIndices.any { it.path == "Patient.birthDate" }).isFalse()
@@ -258,7 +261,7 @@ class ResourceIndexerTest {
         effective = dateTime
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     observation.effectiveDateTimeType
     assertThat(resourceIndices.dateTimeIndices)
@@ -281,7 +284,7 @@ class ResourceIndexerTest {
         effective = instant
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(resourceIndices.dateTimeIndices)
       .contains(
@@ -302,7 +305,7 @@ class ResourceIndexerTest {
         effective = period
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(resourceIndices.dateTimeIndices)
       .contains(
@@ -328,7 +331,7 @@ class ResourceIndexerTest {
         effective = period
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(resourceIndices.dateTimeIndices)
       .contains(
@@ -350,7 +353,7 @@ class ResourceIndexerTest {
         effective = period
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(resourceIndices.dateTimeIndices)
       .contains(DateTimeIndex("date", "Observation.effective", period.start.time, Long.MAX_VALUE))
@@ -370,7 +373,7 @@ class ResourceIndexerTest {
         effective = timing
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(resourceIndices.dateTimeIndices)
       .contains(
@@ -400,7 +403,7 @@ class ResourceIndexerTest {
         effective = timing
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
     assertThat(resourceIndices.dateTimeIndices).isEmpty()
   }
 
@@ -419,7 +422,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
     val dateTime = DateTimeType("2011-06-27T09:30:10+01:00")
     assertThat(resourceIndices.dateTimeIndices)
       .contains(
@@ -439,7 +442,7 @@ class ResourceIndexerTest {
         id = "non-null-id"
         effective = null
       }
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(resourceIndices.dateTimeIndices.any { it.name == "date" }).isFalse()
     assertThat(resourceIndices.dateTimeIndices.any { it.path == "Observation.effective" }).isFalse()
@@ -454,7 +457,7 @@ class ResourceIndexerTest {
         addName(HumanName().addGiven(nameString))
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.stringIndices)
       .contains(StringIndex("given", "Patient.name.given", nameString))
@@ -468,7 +471,7 @@ class ResourceIndexerTest {
         addName(HumanName().addGiven(null))
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(
         resourceIndices.stringIndices.any { stringIndex ->
@@ -489,7 +492,7 @@ class ResourceIndexerTest {
         addName(HumanName().addGiven(""))
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(
         resourceIndices.stringIndices.any { stringIndex ->
@@ -509,7 +512,7 @@ class ResourceIndexerTest {
         deceased = BooleanType(true)
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.tokenIndices)
       .contains(
@@ -535,7 +538,7 @@ class ResourceIndexerTest {
           )
       }
 
-    val resourceIndices = ResourceIndexer.index(invoice)
+    val resourceIndices = resourceIndexer.index(invoice)
 
     assertThat(resourceIndices.tokenIndices)
       .contains(TokenIndex("identifier", "Invoice.identifier", system, value))
@@ -551,7 +554,7 @@ class ResourceIndexerTest {
         code = CodeableConcept().addCoding(Coding().setCode(codeString).setSystem(systemString))
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(resourceIndices.tokenIndices)
       .contains(TokenIndex("code", "Observation.code", systemString, codeString))
@@ -571,7 +574,7 @@ class ResourceIndexerTest {
             display = "Display"
           }
       }
-    val resourceIndices = ResourceIndexer.index(encounter)
+    val resourceIndices = resourceIndexer.index(encounter)
 
     assertThat(resourceIndices.tokenIndices)
       .contains(TokenIndex("class", "Encounter.class", systemString, codeString))
@@ -585,7 +588,7 @@ class ResourceIndexerTest {
         code = null
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(
         resourceIndices.tokenIndices.any { tokenIndex -> tokenIndex.path == "Observation.code" }
@@ -603,7 +606,7 @@ class ResourceIndexerTest {
         code = CodeableConcept().addCoding(Coding())
       }
 
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(
         resourceIndices.tokenIndices.any { tokenIndex -> tokenIndex.path == "Observation.code" }
@@ -622,7 +625,7 @@ class ResourceIndexerTest {
         managingOrganization = Reference().setReference(organizationString)
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.referenceIndices)
       .contains(ReferenceIndex("organization", "Patient.managingOrganization", organizationString))
@@ -645,7 +648,7 @@ class ResourceIndexerTest {
         this.addRelatedArtifact(relatedArtifact)
       }
 
-    val resourceIndices = ResourceIndexer.index(activityDefinition)
+    val resourceIndices = resourceIndexer.index(activityDefinition)
 
     val indexPath =
       "ActivityDefinition.relatedArtifact.where(type='depends-on').resource | ActivityDefinition.library"
@@ -667,7 +670,7 @@ class ResourceIndexerTest {
         this.addAction().definition = UriType("http://action2.com")
       }
 
-    val resourceIndices = ResourceIndexer.index(planDefinition)
+    val resourceIndices = resourceIndexer.index(planDefinition)
 
     val indexPath = "PlanDefinition.action.definition"
     val indexName = PlanDefinition.SP_DEFINITION
@@ -687,7 +690,7 @@ class ResourceIndexerTest {
         managingOrganization = null
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(
         resourceIndices.referenceIndices.any { referenceIndex ->
@@ -712,7 +715,7 @@ class ResourceIndexerTest {
         managingOrganization = Reference().setReference("")
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(
         resourceIndices.referenceIndices.any { referenceIndex ->
@@ -736,7 +739,7 @@ class ResourceIndexerTest {
         gender = Enumerations.AdministrativeGender.UNKNOWN
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.tokenIndices)
       .contains(
@@ -753,7 +756,7 @@ class ResourceIndexerTest {
   fun index_gender_null() {
     val patient = Patient().apply { id = "someID" }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(resourceIndices.tokenIndices.any { it.name == "gender" }).isFalse()
   }
@@ -766,7 +769,7 @@ class ResourceIndexerTest {
         totalNet = Money().setCurrency("EU").setValue(BigDecimal.valueOf(300))
       }
 
-    val resourceIndices = ResourceIndexer.index(testInvoice)
+    val resourceIndices = resourceIndexer.index(testInvoice)
 
     assertThat(resourceIndices.quantityIndices)
       .contains(
@@ -788,7 +791,7 @@ class ResourceIndexerTest {
         instance.add(Substance.SubstanceInstanceComponent().setQuantity(Quantity(100L)))
       }
 
-    val resourceIndices = ResourceIndexer.index(substance)
+    val resourceIndices = resourceIndexer.index(substance)
 
     assertThat(resourceIndices.quantityIndices)
       .contains(
@@ -806,7 +809,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(substance)
+    val resourceIndices = resourceIndexer.index(substance)
 
     assertThat(resourceIndices.quantityIndices)
       .contains(
@@ -822,7 +825,7 @@ class ResourceIndexerTest {
         instance.add(Substance.SubstanceInstanceComponent().setQuantity(null))
       }
 
-    val resourceIndices = ResourceIndexer.index(substance)
+    val resourceIndices = resourceIndexer.index(substance)
 
     assertThat(
         resourceIndices.quantityIndices.any { quantityIndex -> quantityIndex.name == "quantity" }
@@ -847,7 +850,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(substance)
+    val resourceIndices = resourceIndexer.index(substance)
 
     assertThat(resourceIndices.quantityIndices)
       .contains(
@@ -874,7 +877,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(substance)
+    val resourceIndices = resourceIndexer.index(substance)
 
     assertThat(resourceIndices.quantityIndices)
       .contains(
@@ -896,7 +899,7 @@ class ResourceIndexerTest {
         url = "www.someDomainName.someDomain"
       }
 
-    val resourceIndices = ResourceIndexer.index(device)
+    val resourceIndices = resourceIndexer.index(device)
 
     assertThat(resourceIndices.uriIndices)
       .contains(UriIndex("url", "Device.url", "www.someDomainName.someDomain"))
@@ -910,7 +913,7 @@ class ResourceIndexerTest {
         url = null
       }
 
-    val resourceIndices = ResourceIndexer.index(device)
+    val resourceIndices = resourceIndexer.index(device)
 
     assertThat(resourceIndices.uriIndices.any { index -> index.name == "url" }).isFalse()
   }
@@ -923,7 +926,7 @@ class ResourceIndexerTest {
         url = ""
       }
 
-    val resourceIndices = ResourceIndexer.index(device)
+    val resourceIndices = resourceIndexer.index(device)
 
     assertThat(resourceIndices.uriIndices.any { index -> index.name == "url" }).isFalse()
   }
@@ -938,7 +941,7 @@ class ResourceIndexerTest {
         position = Location.LocationPositionComponent(DecimalType(latitude), DecimalType(longitude))
       }
 
-    val resourceIndices = ResourceIndexer.index(location)
+    val resourceIndices = resourceIndexer.index(location)
 
     assertThat(resourceIndices.positionIndices).contains(PositionIndex(latitude, longitude))
   }
@@ -951,7 +954,7 @@ class ResourceIndexerTest {
         position = null
       }
 
-    val resourceIndices = ResourceIndexer.index(location)
+    val resourceIndices = resourceIndexer.index(location)
 
     assertThat(resourceIndices.positionIndices).isEmpty()
   }
@@ -963,7 +966,7 @@ class ResourceIndexerTest {
       TestingUtils(FhirContext.forR4().newJsonParser())
         .readFromFile(Invoice::class.java, "/quantity_test_invoice.json")
 
-    val resourceIndices = ResourceIndexer.index(testInvoice)
+    val resourceIndices = resourceIndexer.index(testInvoice)
 
     assertThat(resourceIndices.resourceId).isEqualTo(testInvoice.logicalId)
 
@@ -1042,7 +1045,7 @@ class ResourceIndexerTest {
       TestingUtils(FhirContext.forR4().newJsonParser())
         .readFromFile(Questionnaire::class.java, "/uri_test_questionnaire.json")
 
-    val resourceIndices = ResourceIndexer.index(testQuestionnaire)
+    val resourceIndices = resourceIndexer.index(testQuestionnaire)
 
     assertThat(resourceIndices.resourceType).isEqualTo(testQuestionnaire.resourceType)
 
@@ -1099,7 +1102,7 @@ class ResourceIndexerTest {
       TestingUtils(FhirContext.forR4().newJsonParser())
         .readFromFile(Patient::class.java, "/date_test_patient.json")
 
-    val resourceIndices = ResourceIndexer.index(testPatient)
+    val resourceIndices = resourceIndexer.index(testPatient)
 
     assertThat(resourceIndices.resourceType).isEqualTo(testPatient.resourceType)
 
@@ -1195,7 +1198,7 @@ class ResourceIndexerTest {
       TestingUtils(FhirContext.forR4().newJsonParser())
         .readFromFile(Location::class.java, "/location-example-hl7hq.json")
 
-    val resourceIndices = ResourceIndexer.index(testLocation)
+    val resourceIndices = resourceIndexer.index(testLocation)
 
     assertThat(resourceIndices.resourceType).isEqualTo(testLocation.resourceType)
 
@@ -1264,7 +1267,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.stringIndices)
       .containsAtLeast(
         StringIndex("name", "Patient.name", "Mr. Pieter van de Heuvel MSc"),
@@ -1280,7 +1283,7 @@ class ResourceIndexerTest {
         addName(HumanName())
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.stringIndices.any { it.name == "name" }).isFalse()
     assertThat(resourceIndices.stringIndices.any { it.name == "phonetic" }).isFalse()
   }
@@ -1300,7 +1303,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.stringIndices.any { it.path == "name" }).isFalse()
     assertThat(resourceIndices.stringIndices.any { it.name == "phonetic" }).isFalse()
   }
@@ -1337,7 +1340,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.stringIndices)
       .containsAtLeast(
         StringIndex("name", "Patient.name", "Prof. Dr. Pieter van de Heuvel MSc Phd"),
@@ -1362,7 +1365,7 @@ class ResourceIndexerTest {
           )
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.stringIndices)
       .contains(
         StringIndex(
@@ -1381,7 +1384,7 @@ class ResourceIndexerTest {
         address = listOf(Address())
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.stringIndices.any { it.name == "address" }).isFalse()
   }
 
@@ -1402,7 +1405,7 @@ class ResourceIndexerTest {
           )
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
     assertThat(resourceIndices.stringIndices.any { it.name == "address" }).isFalse()
   }
 
@@ -1416,7 +1419,7 @@ class ResourceIndexerTest {
         addName(HumanName().addGiven(givenValue))
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(
         resourceIndices.stringIndices.filter {
@@ -1442,7 +1445,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(molecularSequence)
+    val resourceIndices = resourceIndexer.index(molecularSequence)
 
     assertThat(
         resourceIndices.numberIndices.filter {
@@ -1475,7 +1478,7 @@ class ResourceIndexerTest {
         )
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(
         resourceIndices.tokenIndices.filter {
@@ -1518,7 +1521,7 @@ class ResourceIndexerTest {
         instance.add(Substance.SubstanceInstanceComponent().setQuantity(Quantity(values[2])))
       }
 
-    val resourceIndices = ResourceIndexer.index(substance)
+    val resourceIndices = resourceIndexer.index(substance)
 
     assertThat(
         resourceIndices.quantityIndices.filter {
@@ -1542,7 +1545,7 @@ class ResourceIndexerTest {
         addGeneralPractitioner(Reference().apply { reference = values[1] })
       }
 
-    val resourceIndices = ResourceIndexer.index(patient)
+    val resourceIndices = resourceIndexer.index(patient)
 
     assertThat(
         resourceIndices.referenceIndices.filter {
@@ -1574,7 +1577,7 @@ class ResourceIndexerTest {
     // The indexer creates 2 QuantityIndex per valueQuantity in this particular example because each
     // Observation.component.value can be indexed for both [Observation.SP_COMPONENT_VALUE_QUANTITY]
     // and [Observation.SP_COMBO_VALUE_QUANTITY]
-    val resourceIndices = ResourceIndexer.index(observation)
+    val resourceIndices = resourceIndexer.index(observation)
 
     assertThat(resourceIndices.quantityIndices)
       .containsExactly(
@@ -1621,6 +1624,77 @@ class ResourceIndexerTest {
       )
   }
 
+  @Test
+  fun index_custom_search_param() {
+    val patient =
+      Patient().apply {
+        addIdentifier(
+          Identifier().apply {
+            system = "https://custom-identifier-namespace"
+            value = "OfficialIdentifier_DarcySmith_0001"
+          }
+        )
+        addName(
+          HumanName().apply {
+            use = HumanName.NameUse.OFFICIAL
+            family = "Smith"
+            addGiven("Darcy")
+            gender = Enumerations.AdministrativeGender.FEMALE
+            birthDateElement = DateType("1970-01-01")
+          }
+        )
+        addExtension(
+          Extension().apply {
+            url = "http://hl7.org/fhir/StructureDefinition/patient-mothersMaidenName"
+            setValue(StringType("Marca"))
+          }
+        )
+      }
+
+    val resourceIndices =
+      ResourceIndexer(
+          SearchParamDefinitionsProviderImpl(
+            customParams =
+              mapOf(
+                "Patient" to
+                  listOf(
+                    SearchParamDefinition(
+                      name = "mothers-maiden-name",
+                      type = Enumerations.SearchParamType.STRING,
+                      path =
+                        "Patient.extension('http://hl7.org/fhir/StructureDefinition/patient-mothersMaidenName').value.as(String)"
+                    ),
+                    SearchParamDefinition(
+                      name = "identifierPartial",
+                      type = Enumerations.SearchParamType.STRING,
+                      path = "Patient.identifier.value"
+                    )
+                  )
+              )
+          )
+        )
+        .index(patient)
+
+    assertThat(resourceIndices.stringIndices)
+      .containsExactly(
+        StringIndex(
+          name = "mothers-maiden-name",
+          path =
+            "Patient.extension('http://hl7.org/fhir/StructureDefinition/patient-mothersMaidenName').value.as(String)",
+          value = "Marca"
+        ),
+        StringIndex(
+          name = "identifierPartial",
+          path = "Patient.identifier.value",
+          value = "OfficialIdentifier_DarcySmith_0001"
+        ),
+        StringIndex(name = "family", path = "Patient.name.family", value = "Smith"),
+        StringIndex(name = "name", path = "Patient.name", value = "Darcy Smith"),
+        StringIndex(name = "phonetic", path = "Patient.name", value = "Darcy Smith"),
+        StringIndex(name = "given", path = "Patient.name.given", value = "Darcy")
+      )
+  }
+
   private companion object {
     // See: https://www.hl7.org/fhir/valueset-currencies.html
     const val FHIR_CURRENCY_SYSTEM = "urn:iso:std:iso:4217"