diff --git a/gcloud/datastore/batch.py b/gcloud/datastore/batch.py
index de2cb021b39d..2e3a3d8b328f 100644
--- a/gcloud/datastore/batch.py
+++ b/gcloud/datastore/batch.py
@@ -119,7 +119,8 @@ def _add_partial_key_entity_pb(self):
         :returns: The newly created entity protobuf that will be
                   updated and sent with a commit.
         """
-        return self.mutations.insert_auto_id.add()
+        new_mutation = self.mutations.add()
+        return new_mutation.insert
 
     def _add_complete_key_entity_pb(self):
         """Adds a new mutation for an entity with a completed key.
@@ -131,7 +132,8 @@ def _add_complete_key_entity_pb(self):
         # We use ``upsert`` for entities with completed keys, rather than
         # ``insert`` or ``update``, in order not to create race conditions
         # based on prior existence / removal of the entity.
-        return self.mutations.upsert.add()
+        new_mutation = self.mutations.add()
+        return new_mutation.upsert
 
     def _add_delete_key_pb(self):
         """Adds a new mutation for a key to be deleted.
@@ -140,7 +142,8 @@ def _add_delete_key_pb(self):
         :returns: The newly created key protobuf that will be
                   deleted when sent with a commit.
         """
-        return self.mutations.delete.add()
+        new_mutation = self.mutations.add()
+        return new_mutation.delete
 
     @property
     def mutations(self):
@@ -152,10 +155,11 @@ def mutations(self):
         adding a new mutation. This getter returns the protobuf that has been
         built-up so far.
 
-        :rtype: :class:`gcloud.datastore._generated.datastore_pb2.Mutation`
-        :returns: The Mutation protobuf to be sent in the commit request.
+        :rtype: iterable
+        :returns: The list of :class:`._generated.datastore_pb2.Mutation`
+                  protobufs to be sent in the commit request.
         """
-        return self._commit_request.mutation
+        return self._commit_request.mutations
 
     def put(self, entity):
         """Remember an entity's state to be saved during :meth:`commit`.
@@ -172,7 +176,7 @@ def put(self, entity):
            "bytes" ('str' in Python2, 'bytes' in Python3) map to 'blob_value'.
 
         When an entity has a partial key, calling :meth:`commit` sends it as
-        an ``insert_auto_id`` mutation and the key is completed. On return,
+        an ``insert`` mutation and the key is completed. On return,
         the key for the ``entity`` passed in is updated to match the key ID
         assigned by the server.
 
diff --git a/gcloud/datastore/connection.py b/gcloud/datastore/connection.py
index deae2796d516..b3921f8b992f 100644
--- a/gcloud/datastore/connection.py
+++ b/gcloud/datastore/connection.py
@@ -431,7 +431,8 @@ def _parse_commit_response(commit_response_pb):
                :class:`._generated.entity_pb2.Key` for each incomplete key
                that was completed in the commit.
     """
-    mut_result = commit_response_pb.mutation_result
-    index_updates = mut_result.index_updates
-    completed_keys = list(mut_result.insert_auto_id_key)
+    mut_results = commit_response_pb.mutation_results
+    index_updates = commit_response_pb.index_updates
+    completed_keys = [mut_result.key for mut_result in mut_results
+                      if mut_result.HasField('key')]  # Message field (Key)
     return index_updates, completed_keys
diff --git a/gcloud/datastore/helpers.py b/gcloud/datastore/helpers.py
index 269e3e97645c..6ce3e08870e6 100644
--- a/gcloud/datastore/helpers.py
+++ b/gcloud/datastore/helpers.py
@@ -23,7 +23,6 @@
 import six
 
 from gcloud._helpers import _datetime_to_pb_timestamp
-from gcloud._helpers import _has_field
 from gcloud._helpers import _pb_timestamp_to_datetime
 from gcloud.datastore._generated import entity_pb2 as _entity_pb2
 from gcloud.datastore.entity import Entity
diff --git a/gcloud/datastore/test_batch.py b/gcloud/datastore/test_batch.py
index a8d96370cce9..18d79aef94d5 100644
--- a/gcloud/datastore/test_batch.py
+++ b/gcloud/datastore/test_batch.py
@@ -38,7 +38,9 @@ def test_ctor(self):
         self.assertEqual(batch.namespace, _NAMESPACE)
         self.assertTrue(batch._id is None)
         self.assertEqual(batch._status, batch._INITIAL)
-        self.assertTrue(isinstance(batch.mutations, datastore_pb2.Mutation))
+        self.assertTrue(isinstance(batch._commit_request,
+                                   datastore_pb2.CommitRequest))
+        self.assertTrue(batch.mutations is batch._commit_request.mutations)
         self.assertEqual(batch._partial_key_entities, [])
 
     def test_current(self):
@@ -90,7 +92,7 @@ def test_put_entity_w_partial_key(self):
 
         batch.put(entity)
 
-        mutated_entity = _mutated_pb(self, batch.mutations, 'insert_auto_id')
+        mutated_entity = _mutated_pb(self, batch.mutations, 'insert')
         self.assertEqual(mutated_entity.key, key._key)
         self.assertEqual(batch._partial_key_entities, [entity])
 
@@ -121,9 +123,10 @@ def test_put_entity_w_completed_key(self):
         self.assertFalse(prop_dict['foo'].exclude_from_indexes)
         self.assertTrue(prop_dict['baz'].exclude_from_indexes)
         self.assertFalse(prop_dict['spam'].exclude_from_indexes)
-        self.assertTrue(prop_dict['spam'].list_value[0].exclude_from_indexes)
-        self.assertTrue(prop_dict['spam'].list_value[1].exclude_from_indexes)
-        self.assertTrue(prop_dict['spam'].list_value[2].exclude_from_indexes)
+        spam_values = prop_dict['spam'].array_value.values
+        self.assertTrue(spam_values[0].exclude_from_indexes)
+        self.assertTrue(spam_values[1].exclude_from_indexes)
+        self.assertTrue(spam_values[2].exclude_from_indexes)
         self.assertFalse('frotz' in prop_dict)
 
     def test_put_entity_w_completed_key_prefixed_project(self):
@@ -153,9 +156,10 @@ def test_put_entity_w_completed_key_prefixed_project(self):
         self.assertFalse(prop_dict['foo'].exclude_from_indexes)
         self.assertTrue(prop_dict['baz'].exclude_from_indexes)
         self.assertFalse(prop_dict['spam'].exclude_from_indexes)
-        self.assertTrue(prop_dict['spam'].list_value[0].exclude_from_indexes)
-        self.assertTrue(prop_dict['spam'].list_value[1].exclude_from_indexes)
-        self.assertTrue(prop_dict['spam'].list_value[2].exclude_from_indexes)
+        spam_values = prop_dict['spam'].array_value.values
+        self.assertTrue(spam_values[0].exclude_from_indexes)
+        self.assertTrue(spam_values[1].exclude_from_indexes)
+        self.assertTrue(spam_values[2].exclude_from_indexes)
         self.assertFalse('frotz' in prop_dict)
 
     def test_delete_w_partial_key(self):
@@ -424,20 +428,18 @@ def current_batch(self):
             return self._batches[0]
 
 
-def _assert_num_mutations(test_case, mutation_pb, num_mutations):
-    total_mutations = (len(mutation_pb.upsert) +
-                       len(mutation_pb.update) +
-                       len(mutation_pb.insert) +
-                       len(mutation_pb.insert_auto_id) +
-                       len(mutation_pb.delete))
-    test_case.assertEqual(total_mutations, num_mutations)
+def _assert_num_mutations(test_case, mutation_pb_list, num_mutations):
+    test_case.assertEqual(len(mutation_pb_list), num_mutations)
 
 
-def _mutated_pb(test_case, mutation_pb, mutation_type):
+def _mutated_pb(test_case, mutation_pb_list, mutation_type):
     # Make sure there is only one mutation.
-    _assert_num_mutations(test_case, mutation_pb, 1)
+    _assert_num_mutations(test_case, mutation_pb_list, 1)
 
-    mutated_pbs = getattr(mutation_pb, mutation_type, [])
-    # Make sure we have exactly one protobuf.
-    test_case.assertEqual(len(mutated_pbs), 1)
-    return mutated_pbs[0]
+    # We grab the only mutation.
+    mutated_pb = mutation_pb_list[0]
+    # Then check if it is the correct type.
+    test_case.assertEqual(mutated_pb.WhichOneof('operation'),
+                          mutation_type)
+
+    return getattr(mutated_pb, mutation_type)
diff --git a/gcloud/datastore/test_client.py b/gcloud/datastore/test_client.py
index 9908816e3644..35547574c996 100644
--- a/gcloud/datastore/test_client.py
+++ b/gcloud/datastore/test_client.py
@@ -612,6 +612,7 @@ def test_put_multi_no_batch_w_partial_key(self):
         from gcloud.datastore.test_batch import _Entity
         from gcloud.datastore.test_batch import _Key
         from gcloud.datastore.test_batch import _KeyPB
+        from gcloud.datastore.test_batch import _mutated_pb
 
         entity = _Entity(foo=u'bar')
         key = entity.key = _Key(self.PROJECT)
@@ -628,15 +629,16 @@ def test_put_multi_no_batch_w_partial_key(self):
         (project,
          commit_req, transaction_id) = client.connection._commit_cw[0]
         self.assertEqual(project, self.PROJECT)
-        inserts = list(commit_req.mutation.insert_auto_id)
-        self.assertEqual(len(inserts), 1)
-        self.assertEqual(inserts[0].key, key.to_protobuf())
 
-        prop_list = list(_property_tuples(inserts[0]))
+        mutated_entity = _mutated_pb(self, commit_req.mutations, 'insert')
+        self.assertEqual(mutated_entity.key, key.to_protobuf())
+
+        prop_list = list(_property_tuples(mutated_entity))
         self.assertTrue(len(prop_list), 1)
         name, value_pb = prop_list[0]
         self.assertEqual(name, 'foo')
         self.assertEqual(value_pb.string_value, u'bar')
+
         self.assertTrue(transaction_id is None)
 
     def test_put_multi_existing_batch_w_completed_key(self):
@@ -688,6 +690,7 @@ def test_delete_multi_no_keys(self):
 
     def test_delete_multi_no_batch(self):
         from gcloud.datastore.test_batch import _Key
+        from gcloud.datastore.test_batch import _mutated_pb
 
         key = _Key(self.PROJECT)
 
@@ -701,7 +704,9 @@ def test_delete_multi_no_batch(self):
         (project,
          commit_req, transaction_id) = client.connection._commit_cw[0]
         self.assertEqual(project, self.PROJECT)
-        self.assertEqual(list(commit_req.mutation.delete), [key.to_protobuf()])
+
+        mutated_key = _mutated_pb(self, commit_req.mutations, 'delete')
+        self.assertEqual(mutated_key, key.to_protobuf())
         self.assertTrue(transaction_id is None)
 
     def test_delete_multi_w_existing_batch(self):
diff --git a/gcloud/datastore/test_connection.py b/gcloud/datastore/test_connection.py
index f50682b87301..a209b4a8b22c 100644
--- a/gcloud/datastore/test_connection.py
+++ b/gcloud/datastore/test_connection.py
@@ -643,8 +643,8 @@ def test_commit_wo_transaction(self):
         key_pb = self._make_key_pb(PROJECT)
         rsp_pb = datastore_pb2.CommitResponse()
         req_pb = datastore_pb2.CommitRequest()
-        mutation = req_pb.mutation
-        insert = mutation.upsert.add()
+        mutation = req_pb.mutations.add()
+        insert = mutation.upsert
         insert.key.CopyFrom(key_pb)
         value_pb = _new_value_pb(insert, 'foo')
         value_pb.string_value = u'Foo'
@@ -675,7 +675,7 @@ def mock_parse(response):
         request = rq_class()
         request.ParseFromString(cw['body'])
         self.assertEqual(request.transaction, b'')
-        self.assertEqual(request.mutation, mutation)
+        self.assertEqual(list(request.mutations), [mutation])
         self.assertEqual(request.mode, rq_class.NON_TRANSACTIONAL)
         self.assertEqual(_parsed, [rsp_pb])
 
@@ -689,8 +689,8 @@ def test_commit_w_transaction(self):
         key_pb = self._make_key_pb(PROJECT)
         rsp_pb = datastore_pb2.CommitResponse()
         req_pb = datastore_pb2.CommitRequest()
-        mutation = req_pb.mutation
-        insert = mutation.upsert.add()
+        mutation = req_pb.mutations.add()
+        insert = mutation.upsert
         insert.key.CopyFrom(key_pb)
         value_pb = _new_value_pb(insert, 'foo')
         value_pb.string_value = u'Foo'
@@ -721,7 +721,7 @@ def mock_parse(response):
         request = rq_class()
         request.ParseFromString(cw['body'])
         self.assertEqual(request.transaction, b'xact')
-        self.assertEqual(request.mutation, mutation)
+        self.assertEqual(list(request.mutations), [mutation])
         self.assertEqual(request.mode, rq_class.TRANSACTIONAL)
         self.assertEqual(_parsed, [rsp_pb])
 
@@ -833,10 +833,10 @@ def test_it(self):
             ),
         ]
         response = datastore_pb2.CommitResponse(
-            mutation_result=datastore_pb2.MutationResult(
-                index_updates=index_updates,
-                insert_auto_id_key=keys,
-            ),
+            mutation_results=[
+                datastore_pb2.MutationResult(key=key) for key in keys
+            ],
+            index_updates=index_updates,
         )
         result = self._callFUT(response)
         self.assertEqual(result, (index_updates, keys))
diff --git a/gcloud/datastore/test_helpers.py b/gcloud/datastore/test_helpers.py
index 4fd61a036b18..d59f605d278f 100644
--- a/gcloud/datastore/test_helpers.py
+++ b/gcloud/datastore/test_helpers.py
@@ -309,7 +309,7 @@ def test_inverts_to_protobuf(self):
         array_val1.exclude_from_indexes = False
         array_val1.meaning = meaning = 22
         array_val1.blob_value = b'\xe2\x98\x83'
-        array_val2 = val_pb4.array_value.add()
+        array_val2 = val_pb4.array_value.values.add()
         array_val2.exclude_from_indexes = False
         array_val2.meaning = meaning
         array_val2.blob_value = b'\xe2\x98\x85'
diff --git a/gcloud/datastore/test_transaction.py b/gcloud/datastore/test_transaction.py
index d7fb9bc9096b..5f780f63388a 100644
--- a/gcloud/datastore/test_transaction.py
+++ b/gcloud/datastore/test_transaction.py
@@ -35,7 +35,9 @@ def test_ctor_defaults(self):
         self.assertEqual(xact.connection, connection)
         self.assertEqual(xact.id, None)
         self.assertEqual(xact._status, self._getTargetClass()._INITIAL)
-        self.assertTrue(isinstance(xact.mutations, datastore_pb2.Mutation))
+        self.assertTrue(isinstance(xact._commit_request,
+                                   datastore_pb2.CommitRequest))
+        self.assertTrue(xact.mutations is xact._commit_request.mutations)
         self.assertEqual(len(xact._partial_key_entities), 0)
 
     def test_current(self):
diff --git a/gcloud/datastore/transaction.py b/gcloud/datastore/transaction.py
index 25c92729e9ca..41397f354f11 100644
--- a/gcloud/datastore/transaction.py
+++ b/gcloud/datastore/transaction.py
@@ -24,7 +24,7 @@ class Transaction(Batch):
     or none succeed (transactionally).
 
     For example, the following snippet of code will put the two ``save``
-    operations (either ``insert_auto_id`` or ``upsert``) into the same
+    operations (either ``insert`` or ``upsert``) into the same
     mutation, and execute those within a transaction::
 
       >>> from gcloud import datastore