diff --git a/graphene/contrib/django/fields.py b/graphene/contrib/django/fields.py
index 62b39968..f9659a99 100644
--- a/graphene/contrib/django/fields.py
+++ b/graphene/contrib/django/fields.py
@@ -62,7 +62,7 @@ class DjangoModelField(Field):
                     self.object_type
                 )
             )
-        return _type and _type.internal_type(schema) or Field.SKIP
+        return schema.T(_type) or Field.SKIP
 
     def get_object_type(self, schema):
         return get_type_for_model(schema, self.model)
diff --git a/graphene/core/fields.py b/graphene/core/fields.py
index a83ecbf0..f00105e5 100644
--- a/graphene/core/fields.py
+++ b/graphene/core/fields.py
@@ -114,7 +114,7 @@ class Field(object):
         else:
             object_type = self.get_object_type(schema)
             if object_type:
-                field_type = object_type.internal_type(schema)
+                field_type = schema.T(object_type)
 
         field_type = self.type_wrapper(field_type)
         return field_type
diff --git a/graphene/core/schema.py b/graphene/core/schema.py
index 8fa3d340..f4a1b000 100644
--- a/graphene/core/schema.py
+++ b/graphene/core/schema.py
@@ -25,6 +25,7 @@ class Schema(object):
 
     def __init__(self, query=None, mutation=None, name='Schema', executor=None):
         self._internal_types = {}
+        self._types = {}
         self.mutation = mutation
         self.query = query
         self.name = name
@@ -34,6 +35,13 @@ class Schema(object):
     def __repr__(self):
         return '<Schema: %s (%s)>' % (str(self.name), hash(self))
 
+    def T(self, object_type):
+        if not object_type:
+            return
+        if object_type not in self._types:
+            self._types[object_type] = object_type.internal_type(self)
+        return self._types[object_type]
+
     @property
     def query(self):
         return self._query
@@ -41,7 +49,6 @@ class Schema(object):
     @query.setter
     def query(self, query):
         self._query = query
-        self._query_type = query and query.internal_type(self)
 
     @property
     def mutation(self):
@@ -50,7 +57,6 @@ class Schema(object):
     @mutation.setter
     def mutation(self, mutation):
         self._mutation = mutation
-        self._mutation_type = mutation and mutation.internal_type(self)
 
     @property
     def executor(self):
@@ -62,11 +68,11 @@ class Schema(object):
     def executor(self, value):
         self._executor = value
 
-    @cached_property
+    @property
     def schema(self):
-        if not self._query_type:
+        if not self._query:
             raise Exception('You have to define a base query type')
-        return GraphQLSchema(self, query=self._query_type, mutation=self._mutation_type)
+        return GraphQLSchema(self, query=self.T(self._query), mutation=self.T(self._mutation))
 
     def associate_internal_type(self, internal_type, object_type):
         self._internal_types[internal_type.name] = object_type
@@ -76,6 +82,7 @@ class Schema(object):
         return object_type
 
     def get_type(self, type_name):
+        self.schema._build_type_map()
         if type_name not in self._internal_types:
             raise Exception('Type %s not found in %r' % (type_name, self))
         return self._internal_types[type_name]
diff --git a/graphene/core/types.py b/graphene/core/types.py
index d95ab4e8..e9bf78ec 100644
--- a/graphene/core/types.py
+++ b/graphene/core/types.py
@@ -179,15 +179,14 @@ class BaseObjectType(object):
 
     @classmethod
     def resolve_objecttype(cls, schema, instance, *_):
-        return instance
+        return instance.__class__
 
     @classmethod
     def resolve_type(cls, schema, instance, *_):
         objecttype = cls.resolve_objecttype(schema, instance, *_)
-        return objecttype.internal_type(schema)
+        return schema.T(objecttype)
 
     @classmethod
-    @memoize
     @register_internal_type
     def internal_type(cls, schema):
         fields = lambda: OrderedDict([(f.name, f.internal_field(schema))
@@ -203,7 +202,7 @@ class BaseObjectType(object):
         return GraphQLObjectType(
             cls._meta.type_name,
             description=cls._meta.description,
-            interfaces=[i.internal_type(schema) for i in cls._meta.interfaces],
+            interfaces=[schema.T(i) for i in cls._meta.interfaces],
             fields=fields,
             is_type_of=getattr(cls, 'is_type_of', None)
         )
@@ -225,7 +224,6 @@ class Mutation(six.with_metaclass(ObjectTypeMeta, BaseObjectType)):
 
 class InputObjectType(ObjectType):
     @classmethod
-    @memoize
     @register_internal_type
     def internal_type(cls, schema):
         fields = lambda: OrderedDict([(f.name, f.internal_field(schema))
diff --git a/graphene/relay/fields.py b/graphene/relay/fields.py
index 68233b22..8d115d83 100644
--- a/graphene/relay/fields.py
+++ b/graphene/relay/fields.py
@@ -63,8 +63,8 @@ class ConnectionField(Field):
         node = self.get_object_type(schema)
         assert is_node(node), 'Only nodes have connections.'
         schema.register(node)
-
-        return self.get_connection_type(node).internal_type(schema)
+        connection_type = self.get_connection_type(node)
+        return schema.T(connection_type)
 
 
 class NodeField(Field):
diff --git a/tests/contrib_django/test_types.py b/tests/contrib_django/test_types.py
index 62da63c1..6ef741fd 100644
--- a/tests/contrib_django/test_types.py
+++ b/tests/contrib_django/test_types.py
@@ -50,7 +50,7 @@ def test_django_interface():
 
 
 def test_pseudo_interface():
-    object_type = Character.internal_type(schema)
+    object_type = schema.T(Character)
     assert Character._meta.is_interface is True
     assert isinstance(object_type, GraphQLInterfaceType)
     assert Character._meta.model == Reporter
@@ -81,7 +81,7 @@ def test_interface_resolve_type():
 
 
 def test_object_type():
-    object_type = Human.internal_type(schema)
+    object_type = schema.T(Human)
     fields_map = Human._meta.fields_map
     assert Human._meta.is_interface is False
     assert isinstance(object_type, GraphQLObjectType)
@@ -95,7 +95,7 @@ def test_object_type():
     #     'reporter': fields_map['reporter'].internal_field(schema),
     #     'pubDate': fields_map['pub_date'].internal_field(schema),
     # }
-    assert DjangoNode.internal_type(schema) in object_type.get_interfaces()
+    assert schema.T(DjangoNode) in object_type.get_interfaces()
 
 
 def test_node_notinterface():
diff --git a/tests/core/test_query.py b/tests/core/test_query.py
index 33cc60cf..075cdea2 100644
--- a/tests/core/test_query.py
+++ b/tests/core/test_query.py
@@ -46,7 +46,7 @@ class Human(Character):
 
 schema = Schema()
 
-Human_type = Human.internal_type(schema)
+Human_type = schema.T(Human)
 
 
 def test_type():
diff --git a/tests/core/test_schema.py b/tests/core/test_schema.py
index f6e3d849..a310648f 100644
--- a/tests/core/test_schema.py
+++ b/tests/core/test_schema.py
@@ -125,9 +125,23 @@ def test_schema_register():
     class MyType(ObjectType):
         type = StringField(resolve=lambda *_: 'Dog')
 
+    schema.query = MyType
+
     assert schema.get_type('MyType') == MyType
 
 
+def test_schema_register():
+    schema = Schema(name='My own schema')
+
+    @schema.register
+    class MyType(ObjectType):
+        type = StringField(resolve=lambda *_: 'Dog')
+
+    with raises(Exception) as excinfo:
+        schema.get_type('MyType')
+    assert 'base query type' in str(excinfo.value)
+
+
 def test_schema_introspect():
     schema = Schema(name='My own schema')
 
@@ -138,4 +152,3 @@ def test_schema_introspect():
 
     introspection = schema.introspect()
     assert '__schema' in introspection
-
diff --git a/tests/core/test_types.py b/tests/core/test_types.py
index 7d5a17ed..a8370b72 100644
--- a/tests/core/test_types.py
+++ b/tests/core/test_types.py
@@ -38,7 +38,7 @@ schema = Schema()
 
 
 def test_interface():
-    object_type = Character.internal_type(schema)
+    object_type = schema.T(Character)
     assert Character._meta.is_interface is True
     assert isinstance(object_type, GraphQLInterfaceType)
     assert Character._meta.type_name == 'core_Character'
@@ -54,7 +54,7 @@ def test_interface_resolve_type():
 
 
 def test_object_type():
-    object_type = Human.internal_type(schema)
+    object_type = schema.T(Human)
     assert Human._meta.is_interface is False
     assert Human._meta.type_name == 'core_Human'
     assert isinstance(object_type, GraphQLObjectType)
@@ -62,7 +62,7 @@ def test_object_type():
     assert list(object_type.get_fields().keys()) == ['name', 'friends']
     # assert object_type.get_fields() == {'name': Human._meta.fields_map['name'].internal_field(
     #     schema), 'friends': Human._meta.fields_map['friends'].internal_field(schema)}
-    assert object_type.get_interfaces() == [Character.internal_type(schema)]
+    assert object_type.get_interfaces() == [schema.T(Character)]
     assert Human._meta.fields_map['name'].object_type == Human