diff --git a/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterV2.java b/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterV2.java
index afd492ae6b..33abf53bf4 100644
--- a/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterV2.java
+++ b/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterV2.java
@@ -41,8 +41,6 @@
 /**
  * A BigQuery Stream Writer that can be used to write data into BigQuery Table.
  *
- * <p>TODO: Attach traceId.
- *
  * <p>TODO: Support batching.
  *
  * <p>TODO: Support schema change.
@@ -74,6 +72,11 @@ public class StreamWriterV2 implements AutoCloseable {
    */
   private final long maxInflightBytes;
 
+  /*
+   * TraceId for debugging purpose.
+   */
+  private final String traceId;
+
   /*
    * Tracks current inflight requests in the stream.
    */
@@ -143,6 +146,7 @@ private StreamWriterV2(Builder builder) throws IOException {
     this.writerSchema = builder.writerSchema;
     this.maxInflightRequests = builder.maxInflightRequest;
     this.maxInflightBytes = builder.maxInflightBytes;
+    this.traceId = builder.traceId;
     this.waitingRequestQueue = new LinkedList<AppendRequestAndResponse>();
     this.inflightRequestQueue = new LinkedList<AppendRequestAndResponse>();
     if (builder.client == null) {
@@ -433,6 +437,9 @@ private AppendRowsRequest prepareRequestBasedOnPosition(
         requestBuilder.getProtoRowsBuilder().setWriterSchema(this.writerSchema);
       }
       requestBuilder.setWriteStream(this.streamName);
+      if (this.traceId != null) {
+        requestBuilder.setTraceId(this.traceId);
+      }
     } else {
       requestBuilder.clearWriteStream();
       requestBuilder.getProtoRowsBuilder().clearWriterSchema();
@@ -539,6 +546,8 @@ public static final class Builder {
     private CredentialsProvider credentialsProvider =
         BigQueryWriteSettings.defaultCredentialsProviderBuilder().build();
 
+    private String traceId = null;
+
     private Builder(String streamName) {
       this.streamName = Preconditions.checkNotNull(streamName);
       this.client = null;
@@ -591,6 +600,20 @@ public Builder setCredentialsProvider(CredentialsProvider credentialsProvider) {
       return this;
     }
 
+    /**
+     * Sets traceId for debuging purpose. TraceId must follow the format of
+     * CustomerDomain:DebugString, e.g. DATAFLOW:job_id_x.
+     */
+    public Builder setTraceId(String traceId) {
+      int colonIndex = traceId.indexOf(':');
+      if (colonIndex == -1 || colonIndex == 0 || colonIndex == traceId.length() - 1) {
+        throw new IllegalArgumentException(
+            "TraceId must follow the format of A:B. Actual:" + traceId);
+      }
+      this.traceId = traceId;
+      return this;
+    }
+
     /** Builds the {@code StreamWriterV2}. */
     public StreamWriterV2 build() throws IOException {
       return new StreamWriterV2(this);
diff --git a/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterV2Test.java b/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterV2Test.java
index a6b4a1e790..69aa4341a0 100644
--- a/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterV2Test.java
+++ b/google-cloud-bigquerystorage/src/test/java/com/google/cloud/bigquery/storage/v1beta2/StreamWriterV2Test.java
@@ -54,6 +54,7 @@
 public class StreamWriterV2Test {
   private static final Logger log = Logger.getLogger(StreamWriterV2Test.class.getName());
   private static final String TEST_STREAM = "projects/p/datasets/d/tables/t/streams/s";
+  private static final String TEST_TRACE_ID = "DATAFLOW:job_id";
   private FakeScheduledExecutorService fakeExecutor;
   private FakeBigQueryWrite testBigQueryWrite;
   private static MockServiceHelper serviceHelper;
@@ -84,7 +85,7 @@ public void tearDown() throws Exception {
   }
 
   private StreamWriterV2 getTestStreamWriterV2() throws IOException {
-    return StreamWriterV2.newBuilder(TEST_STREAM, client).build();
+    return StreamWriterV2.newBuilder(TEST_STREAM, client).setTraceId(TEST_TRACE_ID).build();
   }
 
   private ProtoSchema createProtoSchema() {
@@ -184,10 +185,12 @@ private void verifyAppendRequests(long appendCount) {
         // First request received by server should have schema and stream name.
         assertTrue(serverRequest.getProtoRows().hasWriterSchema());
         assertEquals(serverRequest.getWriteStream(), TEST_STREAM);
+        assertEquals(serverRequest.getTraceId(), TEST_TRACE_ID);
       } else {
         // Following request should not have schema and stream name.
         assertFalse(serverRequest.getProtoRows().hasWriterSchema());
         assertEquals(serverRequest.getWriteStream(), "");
+        assertEquals(serverRequest.getTraceId(), "");
       }
     }
   }
@@ -209,7 +212,10 @@ public void testBuildBigQueryWriteClientInWriter() throws Exception {
   @Test
   public void testAppendWithRowsSuccess() throws Exception {
     StreamWriterV2 writer =
-        StreamWriterV2.newBuilder(TEST_STREAM, client).setWriterSchema(createProtoSchema()).build();
+        StreamWriterV2.newBuilder(TEST_STREAM, client)
+            .setWriterSchema(createProtoSchema())
+            .setTraceId(TEST_TRACE_ID)
+            .build();
 
     long appendCount = 100;
     for (int i = 0; i < appendCount; i++) {
@@ -269,6 +275,34 @@ public void run() throws Throwable {
     assertTrue(ex.getStatus().getDescription().contains("Writer schema must be provided"));
   }
 
+  @Test
+  public void testInvalidTraceId() throws Exception {
+    assertThrows(
+        IllegalArgumentException.class,
+        new ThrowingRunnable() {
+          @Override
+          public void run() throws Throwable {
+            StreamWriterV2.newBuilder(TEST_STREAM).setTraceId("abc");
+          }
+        });
+    assertThrows(
+        IllegalArgumentException.class,
+        new ThrowingRunnable() {
+          @Override
+          public void run() throws Throwable {
+            StreamWriterV2.newBuilder(TEST_STREAM).setTraceId("abc:");
+          }
+        });
+    assertThrows(
+        IllegalArgumentException.class,
+        new ThrowingRunnable() {
+          @Override
+          public void run() throws Throwable {
+            StreamWriterV2.newBuilder(TEST_STREAM).setTraceId(":abc");
+          }
+        });
+  }
+
   @Test
   public void testAppendSuccessAndConnectionError() throws Exception {
     StreamWriterV2 writer = getTestStreamWriterV2();