diff --git a/graphql/execution/base.py b/graphql/execution/base.py
index d71151a5..33f449d0 100644
--- a/graphql/execution/base.py
+++ b/graphql/execution/base.py
@@ -60,6 +60,9 @@ def to_dict(self, format_error=None, dict_class=OrderedDict):
         if not self.invalid:
             response["data"] = self.data
 
+        if self.extensions:
+            response["extensions"] = self.extensions
+
         return response
 
 
@@ -76,6 +79,7 @@ class ResolveInfo(object):
         "variable_values",
         "context",
         "path",
+        "extensions",
     )
 
     def __init__(
@@ -91,6 +95,7 @@ def __init__(
         variable_values,  # type: Dict
         context,  # type: Optional[Any]
         path=None,  # type: Union[List[Union[int, str]], List[str]]
+        extensions=None,  # type: Dict
     ):
         # type: (...) -> None
         self.field_name = field_name
@@ -104,6 +109,7 @@ def __init__(
         self.variable_values = variable_values
         self.context = context
         self.path = path
+        self.extensions = extensions
 
 
 __all__ = [
diff --git a/graphql/execution/executor.py b/graphql/execution/executor.py
index 1b5e884e..e6b75842 100644
--- a/graphql/execution/executor.py
+++ b/graphql/execution/executor.py
@@ -133,11 +133,17 @@ def on_resolve(data):
         if isinstance(data, Observable):
             return data
 
-        if not exe_context.errors:
+        if exe_context.errors and exe_context.extensions:
+            return ExecutionResult(
+                data=data, errors=exe_context.errors, extensions=exe_context.extensions
+            )
+        elif exe_context.errors:
+            return ExecutionResult(data=data, errors=exe_context.errors)
+        elif exe_context.extensions:
+            return ExecutionResult(data=data, extensions=exe_context.extensions)
+        else:
             return ExecutionResult(data=data)
 
-        return ExecutionResult(data=data, errors=exe_context.errors)
-
     promise = (
         Promise.resolve(None).then(promise_executor).catch(on_rejected).then(on_resolve)
     )
@@ -354,6 +360,7 @@ def resolve_field(
         variable_values=exe_context.variable_values,
         context=context,
         path=field_path,
+        extensions=exe_context.extensions,
     )
 
     executor = exe_context.executor
@@ -408,6 +415,7 @@ def subscribe_field(
         variable_values=exe_context.variable_values,
         context=context,
         path=path,
+        extensions=exe_context.extensions,
     )
 
     executor = exe_context.executor
@@ -531,6 +539,20 @@ def complete_value(
             ),
         )
 
+    # If result is ExecutionResult, update exe_context and complete for data field
+    if isinstance(result, ExecutionResult):
+        data = getattr(result, "data", None)
+        extensions = getattr(result, "extensions", None)
+        errors = getattr(result, "errors", None)
+
+        if extensions:
+            exe_context.update_extensions(extensions)
+        if errors:
+            for error in errors:
+                exe_context.report_error(error)
+
+        return complete_value(exe_context, return_type, field_asts, info, path, data)
+
     # print return_type, type(result)
     if isinstance(result, Exception):
         raise GraphQLLocatedError(field_asts, original_error=result, path=path)
diff --git a/graphql/execution/tests/test_resolve.py b/graphql/execution/tests/test_resolve.py
index d6788f38..e66660d0 100644
--- a/graphql/execution/tests/test_resolve.py
+++ b/graphql/execution/tests/test_resolve.py
@@ -15,6 +15,7 @@
     GraphQLSchema,
     GraphQLString,
 )
+from graphql.execution import ExecutionResult
 from promise import Promise
 
 # from graphql.execution.base import ResolveInfo
@@ -112,6 +113,40 @@ def resolver(source, info, **args):
     ]
 
 
+def test_handles_resolved_extensions_with_data():
+    # type: () -> None
+    def resolver(source, info, **args):
+        # type: (Optional[str], ResolveInfo, **Any) -> ExecutionResult
+        extensions = info.extensions or {}
+        extensions["test_extensions"] = extensions.get("test_extensions", {})
+        extensions["test_extensions"].update({"foo": "bar"})
+        return ExecutionResult(data="foobar", extensions=extensions)
+
+    schema = _test_schema(GraphQLField(GraphQLString, resolver=resolver))
+
+    result = graphql(schema, "{ test }", None)
+    assert not result.errors
+    assert result.data == {"test": "foobar"}
+    assert result.extensions == {"test_extensions": {"foo": "bar"}}
+
+
+def test_handles_resolved_extensions_with_errors():
+    # type: () -> None
+    def resolver(source, info, **args):
+        # type: (Optional[str], ResolveInfo, **Any) -> ExecutionResult
+        extensions = info.extensions or {}
+        extensions["errors"] = extensions.get("errors", {})
+        extensions["errors"].update({"test": {"foo": "bar"}})
+        return ExecutionResult(errors=[Exception()], extensions=extensions)
+
+    schema = _test_schema(GraphQLField(GraphQLString, resolver=resolver))
+
+    result = graphql(schema, "{ test }", None)
+    assert len(result.errors) == 1
+    assert result.data == {"test": None}
+    assert result.extensions == {"errors": {"test": {"foo": "bar"}}}
+
+
 def test_handles_resolved_promises():
     # type: () -> None
     def resolver(source, info, **args):
@@ -125,6 +160,23 @@ def resolver(source, info, **args):
     assert result.data == {"test": "foo"}
 
 
+def test_handles_resolved_promises_extensions():
+    # type: () -> None
+    def resolver(source, info, **args):
+        # type: (Optional[Any], ResolveInfo, **Any) -> Promise
+        extensions = info.extensions or {}
+        extensions["test_extensions"] = extensions.get("test_extensions", {})
+        extensions["test_extensions"].update({"foo": "bar"})
+        return Promise.resolve(ExecutionResult(data="foobar", extensions=extensions))
+
+    schema = _test_schema(GraphQLField(GraphQLString, resolver=resolver))
+
+    result = graphql(schema, "{ test }", None)
+    assert not result.errors
+    assert result.data == {"test": "foobar"}
+    assert result.extensions == {"test_extensions": {"foo": "bar"}}
+
+
 def test_handles_resolved_custom_promises():
     # type: () -> None
     def resolver(source, info, **args):
diff --git a/graphql/execution/utils.py b/graphql/execution/utils.py
index b1e7ff25..13622e39 100644
--- a/graphql/execution/utils.py
+++ b/graphql/execution/utils.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from copy import deepcopy
 import logging
 from traceback import format_exception
 
@@ -54,6 +55,7 @@ class ExecutionContext(object):
         "middleware",
         "allow_subscriptions",
         "_subfields_cache",
+        "extensions",
     )
 
     def __init__(
@@ -67,6 +69,7 @@ def __init__(
         executor,  # type: Any
         middleware,  # type: Optional[Any]
         allow_subscriptions,  # type: bool
+        extensions=None,  # type: Dict
     ):
         # type: (...) -> None
         """Constructs a ExecutionContext object from the arguments passed
@@ -126,6 +129,7 @@ def __init__(
         self.middleware = middleware
         self.allow_subscriptions = allow_subscriptions
         self._subfields_cache = {}  # type: Dict[Tuple[GraphQLObjectType, Tuple[Field, ...]], DefaultOrderedDict]
+        self.extensions = extensions
 
     def get_field_resolver(self, field_resolver):
         # type: (Callable) -> Callable
@@ -151,6 +155,12 @@ def report_error(self, error, traceback=None):
         logger.error("".join(exception))
         self.errors.append(error)
 
+    def update_extensions(self, extensions):
+        # type: (Dict[str, Any]) -> None
+        if extensions:
+            self.extensions = self.extensions or {}
+            self.extensions.update(extensions)
+
     def get_sub_fields(self, return_type, field_asts):
         # type: (GraphQLObjectType, List[Field]) -> DefaultOrderedDict
         k = return_type, tuple(field_asts)