diff --git a/bigquery/storage/managedwriter/integration_test.go b/bigquery/storage/managedwriter/integration_test.go
index e916f6b3449..59930d6b18c 100644
--- a/bigquery/storage/managedwriter/integration_test.go
+++ b/bigquery/storage/managedwriter/integration_test.go
@@ -18,6 +18,7 @@ import (
 	"context"
 	"fmt"
 	"math"
+	"sync"
 	"testing"
 	"time"
 
@@ -633,19 +634,29 @@ func testSchemaEvolution(ctx context.Context, t *testing.T, mwClient *Client, bq
 	if err != nil {
 		t.Errorf("failed to marshal evolved message: %v", err)
 	}
-	result, err = ms.AppendRows(ctx, [][]byte{b}, UpdateSchemaDescriptor(descriptorProto), WithOffset(curOffset))
-	if err != nil {
-		t.Errorf("failed evolved append: %v", err)
-	}
-	_, err = result.GetResult(ctx)
-	if err != nil {
-		t.Errorf("error on evolved append: %v", err)
+	// Try to force connection errors from concurrent appends.
+	// We drop setting of offset to avoid commingling out-of-order append errors.
+	var wg sync.WaitGroup
+	for i := 0; i < 5; i++ {
+		wg.Add(1)
+		go func() {
+			result, err = ms.AppendRows(ctx, [][]byte{b}, UpdateSchemaDescriptor(descriptorProto))
+			if err != nil {
+				t.Errorf("failed evolved append: %v", err)
+			}
+			_, err = result.GetResult(ctx)
+			if err != nil {
+				t.Errorf("error on evolved append: %v", err)
+			}
+			wg.Done()
+		}()
 	}
+	wg.Wait()
 
 	validateTableConstraints(ctx, t, bqClient, testTable, "after send",
-		withExactRowCount(int64(curOffset+1)),
+		withExactRowCount(int64(curOffset+5)),
 		withNullCount("name", 0),
-		withNonNullCount("other", 1),
+		withNonNullCount("other", 5),
 	)
 }
 
diff --git a/bigquery/storage/managedwriter/managed_stream.go b/bigquery/storage/managedwriter/managed_stream.go
index 6e3fa8a95f2..9a1f627a825 100644
--- a/bigquery/storage/managedwriter/managed_stream.go
+++ b/bigquery/storage/managedwriter/managed_stream.go
@@ -174,10 +174,8 @@ func (ms *ManagedStream) Finalize(ctx context.Context, opts ...gax.CallOption) (
 
 // getStream returns either a valid ARC client stream or permanent error.
 //
-// Calling getStream locks the mutex.
+// Any calls to getStream should do so in possesion of the critical section lock.
 func (ms *ManagedStream) getStream(arc *storagepb.BigQueryWrite_AppendRowsClient, forceReconnect bool) (*storagepb.BigQueryWrite_AppendRowsClient, chan *pendingWrite, error) {
-	ms.mu.Lock()
-	defer ms.mu.Unlock()
 	if ms.err != nil {
 		return nil, nil, ms.err
 	}
@@ -205,7 +203,7 @@ func (ms *ManagedStream) getStream(arc *storagepb.BigQueryWrite_AppendRowsClient
 
 // openWithRetry is responsible for navigating the (re)opening of the underlying stream connection.
 //
-// Only getStream() should call this, and thus the calling code has the mutex lock.
+// Only getStream() should call this.
 func (ms *ManagedStream) openWithRetry() (storagepb.BigQueryWrite_AppendRowsClient, chan *pendingWrite, error) {
 	r := defaultRetryer{}
 	for {
@@ -262,12 +260,26 @@ func (ms *ManagedStream) append(requestCtx context.Context, pw *pendingWrite, op
 	var err error
 
 	for {
+		// critical section:  Things that need to happen inside the critical section:
+		//
+		// * Getting the stream connection (in case of reconnects)
+		// * Issuing the append request
+		// * Adding the pending write to the channel to keep ordering correct on response
+		ms.mu.Lock()
+
 		// Don't both calling/retrying if this append's context is already expired.
 		if err = requestCtx.Err(); err != nil {
 			return err
 		}
 
-		arc, ch, err = ms.getStream(arc, pw.newSchema != nil)
+		// If an updated schema is present, we need to reconnect the stream and update the reference
+		// schema for the stream.
+		reconnect := false
+		if pw.newSchema != nil && !proto.Equal(pw.newSchema, ms.schemaDescriptor) {
+			reconnect = true
+			ms.schemaDescriptor = proto.Clone(pw.newSchema).(*descriptorpb.DescriptorProto)
+		}
+		arc, ch, err = ms.getStream(arc, reconnect)
 		if err != nil {
 			return err
 		}
@@ -286,9 +298,6 @@ func (ms *ManagedStream) append(requestCtx context.Context, pw *pendingWrite, op
 			req = reqCopy
 		})
 
-		// critical section:  When we issue an append, we need to add the write to the pending channel
-		// to keep the response ordering correct.
-		ms.mu.Lock()
 		if req != nil {
 			// First append in a new connection needs properties like schema and stream name set.
 			err = (*arc).Send(req)
@@ -342,6 +351,8 @@ func (ms *ManagedStream) Close() error {
 
 	var arc *storagepb.BigQueryWrite_AppendRowsClient
 
+	// Critical section: get connection, close, mark closed.
+	ms.mu.Lock()
 	arc, ch, err := ms.getStream(arc, false)
 	if err != nil {
 		return err
@@ -353,8 +364,9 @@ func (ms *ManagedStream) Close() error {
 	if err == nil {
 		close(ch)
 	}
-	ms.mu.Lock()
 	ms.err = io.EOF
+
+	// Done with the critical section.
 	ms.mu.Unlock()
 	// Propagate cancellation.
 	if ms.cancel != nil {
@@ -383,14 +395,6 @@ func (ms *ManagedStream) AppendRows(ctx context.Context, data [][]byte, opts ...
 		pw.markDone(NoStreamOffset, err, nil)
 		return nil, err
 	}
-	// if we've received an updated schema as part of a write, propagate it to both the cached schema and
-	// populate the schema in the request.
-	if pw.newSchema != nil {
-		ms.schemaDescriptor = pw.newSchema
-		pw.request.GetProtoRows().WriterSchema = &storagepb.ProtoSchema{
-			ProtoDescriptor: pw.newSchema,
-		}
-	}
 	// Call the underlying append.  The stream has it's own retained context and will surface expiry on
 	// it's own, but we also need to respect any deadline for the provided context.
 	errCh := make(chan error)