diff --git a/docs/types/interfaces.rst b/docs/types/interfaces.rst
index 21cf21732..05623dbaa 100644
--- a/docs/types/interfaces.rst
+++ b/docs/types/interfaces.rst
@@ -154,7 +154,7 @@ Interfaces you might come across this error:
 
 This happens because Graphene doesn't have enough information to convert the
 data object into a Graphene type needed to resolve the ``Interface``. To solve
-this you can define a ``resolve_type`` class method on the ``Interface`` which
+this you can define a ``_resolve_type`` class method on the ``Interface`` which
 maps a data object to a Graphene type:
 
 .. code:: python
@@ -164,7 +164,7 @@ maps a data object to a Graphene type:
         name = graphene.String(required=True)
 
         @classmethod
-        def resolve_type(cls, instance, info):
+        def _resolve_type(cls, instance, info):
             if instance.type == 'DROID':
                 return Droid
             return Human
diff --git a/graphene/types/interface.py b/graphene/types/interface.py
index dbc3b4760..f8227cdc1 100644
--- a/graphene/types/interface.py
+++ b/graphene/types/interface.py
@@ -42,7 +42,7 @@ def __init_subclass_with_meta__(cls, _meta=None, **options):
         super(Interface, cls).__init_subclass_with_meta__(_meta=_meta, **options)
 
     @classmethod
-    def resolve_type(cls, instance, info):
+    def _resolve_type(cls, instance, info):
         from .objecttype import ObjectType
         if isinstance(instance, ObjectType):
             return type(instance)
diff --git a/graphene/types/typemap.py b/graphene/types/typemap.py
index b2bc4a0e9..2b8856b0d 100644
--- a/graphene/types/typemap.py
+++ b/graphene/types/typemap.py
@@ -194,8 +194,8 @@ def construct_interface(self, map, type):
             return _type
 
         _resolve_type = None
-        if type.resolve_type:
-            _resolve_type = partial(resolve_type, type.resolve_type, map,
+        if type._resolve_type:
+            _resolve_type = partial(resolve_type, type._resolve_type, map,
                                     type._meta.name)
         return GrapheneInterfaceType(
             graphene_type=type,
@@ -216,8 +216,8 @@ def construct_inputobjecttype(self, map, type):
 
     def construct_union(self, map, type):
         _resolve_type = None
-        if type.resolve_type:
-            _resolve_type = partial(resolve_type, type.resolve_type, map,
+        if type._resolve_type:
+            _resolve_type = partial(resolve_type, type._resolve_type, map,
                                     type._meta.name)
 
         def types():
diff --git a/graphene/types/union.py b/graphene/types/union.py
index 45e03b0c7..d1fab3576 100644
--- a/graphene/types/union.py
+++ b/graphene/types/union.py
@@ -40,7 +40,7 @@ def get_type(cls):
         return cls
 
     @classmethod
-    def resolve_type(cls, instance, info):
+    def _resolve_type(cls, instance, info):
         from .objecttype import ObjectType  # NOQA
         if isinstance(instance, ObjectType):
             return type(instance)