diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index a5604112664d..2128fc9834fb 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -5,6 +5,9 @@ CHANGELOG
 Next Release (TBD)
 ==================
 
+* bugfix:``aws datapipeline``: Fix issue when serializing
+  pipeline definitions containing list elements
+  (`issue 705 <https://github.com/aws/aws-cli/issues/705>`__)
 * bugfix:``aws s3``: Fix issue when recursively removing keys
   containing control characters
   (`issue 675 <https://github.com/aws/aws-cli/issues/675>`__)
diff --git a/awscli/customizations/datapipeline/translator.py b/awscli/customizations/datapipeline/translator.py
index d52198de75e2..48104cb7c438 100644
--- a/awscli/customizations/datapipeline/translator.py
+++ b/awscli/customizations/datapipeline/translator.py
@@ -44,17 +44,25 @@ def definition_to_api(definition):
         # with a 'key', 'stringValue'|'refValue'
         fields = []
         for key, value in sorted(element.items()):
-            field = {'key': key}
-            if isinstance(value, dict) and list(value.keys()) == ['ref']:
-                field['refValue'] = value['ref']
+            if isinstance(value, list):
+                for item in value:
+                    fields.append(_convert_single_field(key, item))
             else:
-                field['stringValue'] = value
-            fields.append(field)
+                fields.append(_convert_single_field(key, value))
         api_object['fields'] = fields
         api_elements.append(api_object)
     return api_elements
 
 
+def _convert_single_field(key, value):
+    field = {'key': key}
+    if isinstance(value, dict) and list(value.keys()) == ['ref']:
+        field['refValue'] = value['ref']
+    else:
+        field['stringValue'] = value
+    return field
+
+
 def api_to_definition(api_response):
     # When we're translating from api_response -> definition
     # we have to be careful *not* to mutate the existing
diff --git a/tests/unit/customizations/datapipeline/test_translator.py b/tests/unit/customizations/datapipeline/test_translator.py
index 5eeb124ee166..9696257e3cd4 100644
--- a/tests/unit/customizations/datapipeline/test_translator.py
+++ b/tests/unit/customizations/datapipeline/test_translator.py
@@ -12,7 +12,6 @@
 # language governing permissions and limitations under the License.
 from tests import unittest
 
-import mock
 from botocore.compat import OrderedDict, json
 
 from awscli.customizations.datapipeline import translator
@@ -114,6 +113,44 @@ def test_missing_id_field(self):
         with self.assertRaises(translator.PipelineDefinitionError):
             translator.definition_to_api(definition)
 
+    def test_list_value_with_strings(self):
+        definition = self.load_def("""{"objects": [
+            {
+              "id" : "emrActivity",
+              "type" : "EmrActivity",
+              "name" : "Foo",
+              "step" : ["s3://foo1", "s3://foo2", "s3://foo3"]
+            }
+        ]}""")
+        actual = translator.definition_to_api(definition)
+        api = [{"name": "Foo", "id": "emrActivity",
+                "fields": [
+                    {"key": "step", "stringValue": "s3://foo1"},
+                    {"key": "step", "stringValue": "s3://foo2"},
+                    {"key": "step", "stringValue": "s3://foo3"},
+                    {"key": "type", "stringValue": "EmrActivity"},
+        ]}]
+        self.assertEqual(actual, api)
+
+    def test_value_with_refs(self):
+        definition = self.load_def("""{"objects": [
+            {
+              "id" : "emrActivity",
+              "type" : "EmrActivity",
+              "name" : "Foo",
+              "step" : ["s3://foo1", {"ref": "otherValue"}, "s3://foo3"]
+            }
+        ]}""")
+        actual = translator.definition_to_api(definition)
+        api = [{"name": "Foo", "id": "emrActivity",
+                "fields": [
+                    {"key": "step", "stringValue": "s3://foo1"},
+                    {"key": "step", "refValue": "otherValue"},
+                    {"key": "step", "stringValue": "s3://foo3"},
+                    {"key": "type", "stringValue": "EmrActivity"},
+        ]}]
+        self.assertEqual(actual, api)
+
     # These tests check the API -> DF conversion.
     def test_api_to_df(self):
         api = [{"name": "S3ToS3Copy", "id": "S3ToS3Copy",