diff --git a/firestore/google/cloud/firestore_v1beta1/query.py b/firestore/google/cloud/firestore_v1beta1/query.py
index 2710e2e97026..14794da0103e 100644
--- a/firestore/google/cloud/firestore_v1beta1/query.py
+++ b/firestore/google/cloud/firestore_v1beta1/query.py
@@ -39,6 +39,7 @@
     _EQ_OP: enums.StructuredQuery.FieldFilter.Operator.EQUAL,
     '>=': enums.StructuredQuery.FieldFilter.Operator.GREATER_THAN_OR_EQUAL,
     '>': enums.StructuredQuery.FieldFilter.Operator.GREATER_THAN,
+    'array_contains': enums.StructuredQuery.FieldFilter.Operator.ARRAY_CONTAINS,
 }
 _BAD_OP_STRING = 'Operator string {!r} is invalid. Valid choices are: {}.'
 _BAD_OP_NAN_NULL = (
diff --git a/firestore/tests/unit/test_query.py b/firestore/tests/unit/test_query.py
index 98d3f7b4fdd8..7979a79bf2b1 100644
--- a/firestore/tests/unit/test_query.py
+++ b/firestore/tests/unit/test_query.py
@@ -965,6 +965,7 @@ def test_success(self):
         self.assertEqual(self._call_fut('=='), op_class.EQUAL)
         self.assertEqual(self._call_fut('>='), op_class.GREATER_THAN_OR_EQUAL)
         self.assertEqual(self._call_fut('>'), op_class.GREATER_THAN)
+        self.assertEqual(self._call_fut('array_contains'), op_class.ARRAY_CONTAINS)
 
     def test_failure(self):
         with self.assertRaises(ValueError):