diff --git a/bandwidth/models/bxml/verbs/start_stream.py b/bandwidth/models/bxml/verbs/start_stream.py
index a4fd274b..0d8768db 100644
--- a/bandwidth/models/bxml/verbs/start_stream.py
+++ b/bandwidth/models/bxml/verbs/start_stream.py
@@ -15,15 +15,16 @@ class StartStream(NestableVerb):
 
     def __init__(
         self, destination: str, stream_params: List[StreamParam] = [],
-        name: str=None, tracks: str=None,
+        name: str=None, mode: str=None, tracks: str=None,
         stream_event_url: str=None,
         stream_event_method: str=None,
         username: str=None, password: str=None,
     ):
-        """Initialize a <Transfer> verb
+        """Initialize a <StartStream> verb
 
         Args:
             name (str, optional): A name to refer to this stream by. Used when sending <StopStream>. If not provided, it will default to the generated stream id as sent in the Media Stream Started webhook.
+            mode (str, optional): The mode to use for the stream. unidirectional or bidirectional. Specifies whether the audio being streamed over the WebSocket is bidirectional (the service can both read and write audio over the WebSocket) or unidirectional (one-way, read-only). Default is unidirectional.
             tracks (str, optional): The part of the call to send a stream from. inbound, outbound or both. Default is inbound.
             destination (str, optional): A websocket URI to send the stream to. The audio from the specified tracks will be sent via websocket to this URL as base64-encoded PCMU/G711 audio. See below for more details on the websocket packet format.
             stream_event_url (str, optional): URL to send the associated Webhook events to during this stream's lifetime. Does not accept BXML. May be a relative URL.
@@ -38,6 +39,7 @@ def __init__(
         self.destination = destination
         self.stream_params = stream_params
         self.name = name
+        self.mode = mode
         self.tracks = tracks
         self.stream_event_url = stream_event_url
         self.stream_event_method = stream_event_method
@@ -53,6 +55,7 @@ def _attributes(self):
         return {
             "destination": self.destination,
             "name": self.name,
+            "mode": self.mode,
             "tracks": self.tracks,
             "streamEventUrl": self.stream_event_url,
             "streamEventMethod": self.stream_event_method,
diff --git a/test/unit/models/bxml/test_start_stream.py b/test/unit/models/bxml/test_start_stream.py
index 8013e916..a934ce46 100644
--- a/test/unit/models/bxml/test_start_stream.py
+++ b/test/unit/models/bxml/test_start_stream.py
@@ -26,6 +26,7 @@ def setUp(self):
         self.start_stream = StartStream(
             stream_params=[self.stream_param1],
             name = "stream1",
+            mode = "bidirectional",
             tracks = "inbound",
             destination = "testurl.com",
             stream_event_url="eventurl.com",
@@ -40,10 +41,10 @@ def test_instance(self):
         assert isinstance(self.start_stream, Verb)
 
     def test_to_bxml(self):
-        expected = '<StartStream destination="testurl.com" name="stream1" tracks="inbound" streamEventUrl="eventurl.com" streamEventMethod="POST" username="user" password="pass"><StreamParam name="name1" value="value1" /></StartStream>'
+        expected = '<StartStream destination="testurl.com" name="stream1" mode="bidirectional" tracks="inbound" streamEventUrl="eventurl.com" streamEventMethod="POST" username="user" password="pass"><StreamParam name="name1" value="value1" /></StartStream>'
         assert expected == self.start_stream.to_bxml()
 
     def test_add_verb(self):
-        expected = '<StartStream destination="testurl.com" name="stream1" tracks="inbound" streamEventUrl="eventurl.com" streamEventMethod="POST" username="user" password="pass"><StreamParam name="name1" value="value1" /><StreamParam name="name2" value="value2" /></StartStream>'
+        expected = '<StartStream destination="testurl.com" name="stream1" mode="bidirectional" tracks="inbound" streamEventUrl="eventurl.com" streamEventMethod="POST" username="user" password="pass"><StreamParam name="name1" value="value1" /><StreamParam name="name2" value="value2" /></StartStream>'
         self.start_stream.add_verb(self.stream_param2)
         assert expected == self.start_stream.to_bxml()