diff --git a/pubsub/integration_test.go b/pubsub/integration_test.go
index d39f458ff407..8b8b8ca3841f 100644
--- a/pubsub/integration_test.go
+++ b/pubsub/integration_test.go
@@ -333,7 +333,13 @@ func testPublishAndReceive(t *testing.T, client *Client, maxMsgs int, synchronou
 		timeout := 3 * time.Minute
 		timeoutCtx, cancel := context.WithTimeout(ctx, timeout)
 		defer cancel()
-		gotMsgs, err := pullN(timeoutCtx, sub, len(want), func(ctx context.Context, m *Message) {
+		gotMsgs, err := pullN(timeoutCtx, sub, len(want), 2*time.Second, func(ctx context.Context, m *Message) {
+			if exactlyOnceDelivery {
+				if _, err := m.AckWithResult().Get(ctx); err != nil {
+					t.Fatalf("failed to ack message with exactly once delivery: %v", err)
+				}
+				return
+			}
 			m.Ack()
 		})
 		if err != nil {
@@ -2003,16 +2009,13 @@ func TestIntegration_TopicRetention(t *testing.T) {
 	}
 }
 
-func TestExactlyOnceDelivery_PublishReceive(t *testing.T) {
+func TestIntegration_ExactlyOnceDelivery_PublishReceive(t *testing.T) {
 	ctx := context.Background()
 	client := integrationTestClient(ctx, t)
 
 	for _, maxMsgs := range []int{0, 3, -1} { // MaxOutstandingMessages = default, 3, unlimited
 		testPublishAndReceive(t, client, maxMsgs, false, true, 10, 0)
 	}
-
-	// Tests for large messages (larger than the 4MB gRPC limit).
-	testPublishAndReceive(t, client, 0, false, true, 1, 5*1024*1024)
 }
 
 func TestIntegration_TopicUpdateSchema(t *testing.T) {
diff --git a/pubsub/message.go b/pubsub/message.go
index 94010cd0cd22..33d87735cb41 100644
--- a/pubsub/message.go
+++ b/pubsub/message.go
@@ -157,20 +157,20 @@ func (ah *psAckHandler) OnNack() {
 }
 
 func (ah *psAckHandler) OnAckWithResult() *AckResult {
+	// call done with true to indicate ack.
+	ah.done(true)
 	if !ah.exactlyOnceDelivery {
 		return newSuccessAckResult()
 	}
-	// call done with true to indicate ack.
-	ah.done(true)
 	return ah.ackResult
 }
 
 func (ah *psAckHandler) OnNackWithResult() *AckResult {
+	// call done with false to indicate nack.
+	ah.done(false)
 	if !ah.exactlyOnceDelivery {
 		return newSuccessAckResult()
 	}
-	// call done with false to indicate nack.
-	ah.done(false)
 	return ah.ackResult
 }
 
diff --git a/pubsub/streaming_pull_test.go b/pubsub/streaming_pull_test.go
index a5a48a1e17ff..de832f1c7152 100644
--- a/pubsub/streaming_pull_test.go
+++ b/pubsub/streaming_pull_test.go
@@ -66,7 +66,7 @@ func TestStreamingPullMultipleFetches(t *testing.T) {
 
 func testStreamingPullIteration(t *testing.T, client *Client, server *mockServer, msgs []*pb.ReceivedMessage) {
 	sub := client.Subscription("S")
-	gotMsgs, err := pullN(context.Background(), sub, len(msgs), func(_ context.Context, m *Message) {
+	gotMsgs, err := pullN(context.Background(), sub, len(msgs), 0, func(_ context.Context, m *Message) {
 		id, err := strconv.Atoi(msgAckID(m))
 		if err != nil {
 			t.Fatalf("pullN err: %v", err)
@@ -196,7 +196,7 @@ func TestStreamingPullRetry(t *testing.T) {
 
 	sub := client.Subscription("S")
 	sub.ReceiveSettings.NumGoroutines = 1
-	gotMsgs, err := pullN(context.Background(), sub, len(testMessages), func(_ context.Context, m *Message) {
+	gotMsgs, err := pullN(context.Background(), sub, len(testMessages), 0, func(_ context.Context, m *Message) {
 		id, err := strconv.Atoi(msgAckID(m))
 		if err != nil {
 			t.Fatalf("pullN err: %v", err)
@@ -297,7 +297,7 @@ func TestStreamingPullConcurrent(t *testing.T) {
 	sub := client.Subscription("S")
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
 	defer cancel()
-	gotMsgs, err := pullN(ctx, sub, nMessages, func(ctx context.Context, m *Message) {
+	gotMsgs, err := pullN(ctx, sub, nMessages, 0, func(ctx context.Context, m *Message) {
 		m.Ack()
 	})
 	if c := status.Convert(err); err != nil && c.Code() != codes.Canceled {
@@ -513,7 +513,8 @@ func newMock(t *testing.T) (*Client, *mockServer) {
 }
 
 // pullN calls sub.Receive until at least n messages are received.
-func pullN(ctx context.Context, sub *Subscription, n int, f func(context.Context, *Message)) ([]*Message, error) {
+// Wait a provided duration before cancelling.
+func pullN(ctx context.Context, sub *Subscription, n int, wait time.Duration, f func(context.Context, *Message)) ([]*Message, error) {
 	var (
 		mu   sync.Mutex
 		msgs []*Message
@@ -526,6 +527,9 @@ func pullN(ctx context.Context, sub *Subscription, n int, f func(context.Context
 		mu.Unlock()
 		f(ctx, m)
 		if nSeen >= n {
+			// Wait a specified amount of time so that for exactly once delivery,
+			// Acks aren't cancelled immediately.
+			time.Sleep(wait)
 			cancel()
 		}
 	})
diff --git a/pubsub/subscription.go b/pubsub/subscription.go
index 0f7c23804d86..7edd7ad2d4c2 100644
--- a/pubsub/subscription.go
+++ b/pubsub/subscription.go
@@ -397,8 +397,8 @@ type SubscriptionConfig struct {
 	// by Pub/Sub and have distinct MessageID values.
 	//
 	// Lastly, to guarantee messages have been acked or nacked properly, you must
-	// call Message.AckWithResponse() or Message.NackWithResponse(). These return an
-	// AckResponse which will be ready if the message has been acked (or failed to be acked).
+	// call Message.AckWithResult() or Message.NackWithResult(). These return an
+	// AckResult which will be ready if the message has been acked (or failed to be acked).
 	EnableExactlyOnceDelivery bool
 
 	// State indicates whether or not the subscription can receive messages.
diff --git a/pubsub/subscription_test.go b/pubsub/subscription_test.go
index bcbbd1f355d2..ed8c865480a6 100644
--- a/pubsub/subscription_test.go
+++ b/pubsub/subscription_test.go
@@ -296,7 +296,7 @@ func testReceive(t *testing.T, synchronous, exactlyOnceDelivery bool) {
 			srv.Publish(topic.name, []byte{byte(i)}, nil)
 		}
 		sub.ReceiveSettings.Synchronous = synchronous
-		msgs, err := pullN(ctx, sub, 256, func(_ context.Context, m *Message) {
+		msgs, err := pullN(ctx, sub, 256, 0, func(_ context.Context, m *Message) {
 			if exactlyOnceDelivery {
 				ar := m.AckWithResult()
 				// Don't use the above ctx here since that will get cancelled.