diff --git a/tests/unit/base/test_serialize.py b/tests/unit/base/test_serialize.py
index 204fe2c2a..57891a65b 100644
--- a/tests/unit/base/test_serialize.py
+++ b/tests/unit/base/test_serialize.py
@@ -90,6 +90,28 @@ def test_list(self):
         self.assertEqual({}, actual)
 
 
+class BooleanTestCase(unittest.TestCase):
+    def test_none(self):
+        value = None
+        actual = serialize.boolean_to_string(value)
+        self.assertIsNone(actual)
+
+    def test_string(self):
+        value = "True"
+        actual = serialize.boolean_to_string(value)
+        self.assertEqual("true", actual)
+
+    def test_bool_true(self):
+        value = True
+        actual = serialize.boolean_to_string(value)
+        self.assertEqual("true", actual)
+
+    def test_bool_false(self):
+        value = False
+        actual = serialize.boolean_to_string(value)
+        self.assertEqual("false", actual)
+
+
 class ObjectTestCase(unittest.TestCase):
     def test_object(self):
         actual = serialize.object({"twilio": "rocks"})
diff --git a/twilio/base/serialize.py b/twilio/base/serialize.py
index 3abc0defe..eac2e12c2 100644
--- a/twilio/base/serialize.py
+++ b/twilio/base/serialize.py
@@ -61,6 +61,16 @@ def flatten_dict(d, result=None, prv_keys=None):
     return {}
 
 
+def boolean_to_string(bool_or_str):
+    if bool_or_str is None:
+        return bool_or_str
+
+    if isinstance(bool_or_str, str):
+        return bool_or_str.lower()
+
+    return "true" if bool_or_str else "false"
+
+
 def object(obj):
     """
     Return a jsonified string represenation of obj if obj is jsonifiable else