diff --git a/src/main/kotlin/org/wfanet/measurement/kingdom/service/api/v2alpha/EventGroupMetadataDescriptorsService.kt b/src/main/kotlin/org/wfanet/measurement/kingdom/service/api/v2alpha/EventGroupMetadataDescriptorsService.kt
index e6a6d474304..0a828191840 100644
--- a/src/main/kotlin/org/wfanet/measurement/kingdom/service/api/v2alpha/EventGroupMetadataDescriptorsService.kt
+++ b/src/main/kotlin/org/wfanet/measurement/kingdom/service/api/v2alpha/EventGroupMetadataDescriptorsService.kt
@@ -14,6 +14,7 @@
 
 package org.wfanet.measurement.kingdom.service.api.v2alpha
 
+import com.google.protobuf.Descriptors.DescriptorValidationException
 import io.grpc.Status
 import io.grpc.StatusException
 import kotlin.math.min
@@ -41,6 +42,7 @@ import org.wfanet.measurement.api.v2alpha.eventGroupMetadataDescriptor
 import org.wfanet.measurement.api.v2alpha.listEventGroupMetadataDescriptorsPageToken
 import org.wfanet.measurement.api.v2alpha.listEventGroupMetadataDescriptorsResponse
 import org.wfanet.measurement.api.v2alpha.principalFromCurrentContext
+import org.wfanet.measurement.common.ProtoReflection
 import org.wfanet.measurement.common.api.ResourceKey
 import org.wfanet.measurement.common.base64UrlDecode
 import org.wfanet.measurement.common.base64UrlEncode
@@ -135,6 +137,15 @@ class EventGroupMetadataDescriptorsService(
       }
     }
 
+    // Check if the FileDescriptorSet is valid by trying to build a list of Descriptors from it.
+    try {
+      ProtoReflection.buildDescriptors(listOf(request.eventGroupMetadataDescriptor.descriptorSet))
+    } catch (e: DescriptorValidationException) {
+      throw Status.INVALID_ARGUMENT.withCause(e)
+        .withDescription("descriptor_set is invalid")
+        .asRuntimeException()
+    }
+
     val createRequest =
       request.eventGroupMetadataDescriptor.toInternal(
         parentKey.dataProviderId,
diff --git a/src/test/kotlin/org/wfanet/measurement/kingdom/service/api/v2alpha/EventGroupMetadataDescriptorsServiceTest.kt b/src/test/kotlin/org/wfanet/measurement/kingdom/service/api/v2alpha/EventGroupMetadataDescriptorsServiceTest.kt
index 6a4dcb76af3..937df140dda 100644
--- a/src/test/kotlin/org/wfanet/measurement/kingdom/service/api/v2alpha/EventGroupMetadataDescriptorsServiceTest.kt
+++ b/src/test/kotlin/org/wfanet/measurement/kingdom/service/api/v2alpha/EventGroupMetadataDescriptorsServiceTest.kt
@@ -17,6 +17,7 @@ package org.wfanet.measurement.kingdom.service.api.v2alpha
 import com.google.common.truth.Truth.assertThat
 import com.google.common.truth.extensions.proto.ProtoTruth.assertThat
 import com.google.protobuf.DescriptorProtos.FileDescriptorSet
+import com.google.protobuf.TextFormat
 import io.grpc.Status
 import io.grpc.StatusRuntimeException
 import kotlin.test.assertFailsWith
@@ -234,6 +235,47 @@ class EventGroupMetadataDescriptorsServiceTest {
     assertThat(exception.status.code).isEqualTo(Status.Code.PERMISSION_DENIED)
   }
 
+  @Test
+  fun `createEventGroupMetadataDescriptor throws INVALID_ARGUMENT when descriptorSet invalid`() {
+    val badFileDescriptorSetText =
+      """
+      file {
+        name: ""
+        package: ""
+        message_type {
+          name: ""
+          field {
+            name: "test"
+            number: 1
+            label: LABEL_OPTIONAL
+            type: TYPE_STRING
+          }
+        }
+      }
+      """
+        .trimIndent()
+
+    val badFileDescriptorSetBuilder = FileDescriptorSet.newBuilder()
+    TextFormat.getParser().merge(badFileDescriptorSetText, badFileDescriptorSetBuilder)
+
+    val request = createEventGroupMetadataDescriptorRequest {
+      parent = DATA_PROVIDER_NAME
+      eventGroupMetadataDescriptor =
+        EVENT_GROUP_METADATA_DESCRIPTOR.copy {
+          clearDescriptorSet()
+          descriptorSet = badFileDescriptorSetBuilder.build()
+        }
+    }
+
+    val exception =
+      assertFailsWith<StatusRuntimeException> {
+        withDataProviderPrincipal(DATA_PROVIDER_NAME) {
+          runBlocking { service.createEventGroupMetadataDescriptor(request) }
+        }
+      }
+    assertThat(exception.status.code).isEqualTo(Status.Code.INVALID_ARGUMENT)
+  }
+
   @Test
   fun `createEventGroupMetadataDescriptor throws INVALID_ARGUMENT when parent is missing`() {
     val exception =