diff --git a/rest_framework/schemas.py b/rest_framework/schemas.py
index 6b6324033c..0618e94fd2 100644
--- a/rest_framework/schemas.py
+++ b/rest_framework/schemas.py
@@ -39,6 +39,10 @@ class SchemaGenerator(object):
         'patch': 'partial_update',
         'delete': 'destroy',
     }
+    known_actions = (
+        'create', 'read', 'retrieve', 'list',
+        'update', 'partial_update', 'destroy'
+    )
 
     def __init__(self, title=None, url=None, patterns=None, urlconf=None):
         assert coreapi, '`coreapi` must be installed for schema support.'
@@ -118,7 +122,8 @@ def get_api_endpoints(self, patterns, prefix=''):
                 if self.should_include_endpoint(path, callback):
                     for method in self.get_allowed_methods(callback):
                         action = self.get_action(path, method, callback)
-                        endpoint = (path, method, action, callback)
+                        category = self.get_category(path, method, callback, action)
+                        endpoint = (path, method, category, action, callback)
                         api_endpoints.append(endpoint)
 
             elif isinstance(pattern, RegexURLResolver):
@@ -128,21 +133,7 @@ def get_api_endpoints(self, patterns, prefix=''):
                 )
                 api_endpoints.extend(nested_endpoints)
 
-        return self.add_categories(api_endpoints)
-
-    def add_categories(self, api_endpoints):
-        """
-        (path, method, action, callback) -> (path, method, category, action, callback)
-        """
-        # Determine the top level categories for the schema content,
-        # based on the URLs of the endpoints. Eg `set(['users', 'organisations'])`
-        paths = [endpoint[0] for endpoint in api_endpoints]
-        categories = self.get_categories(paths)
-
-        return [
-            (path, method, self.get_category(categories, path), action, callback)
-            for (path, method, action, callback) in api_endpoints
-        ]
+        return api_endpoints
 
     def get_path(self, path_regex):
         """
@@ -181,36 +172,41 @@ def get_allowed_methods(self, callback):
 
     def get_action(self, path, method, callback):
         """
-        Return a description action string for the endpoint, eg. 'list'.
+        Return a descriptive action string for the endpoint, eg. 'list'.
         """
         actions = getattr(callback, 'actions', self.default_mapping)
         return actions[method.lower()]
 
-    def get_categories(self, paths):
-        categories = set()
-        split_paths = set([
-            tuple(path.split("{")[0].strip('/').split('/'))
-            for path in paths
-        ])
-
-        while split_paths:
-            for split_path in list(split_paths):
-                if len(split_path) == 0:
-                    split_paths.remove(split_path)
-                elif len(split_path) == 1:
-                    categories.add(split_path[0])
-                    split_paths.remove(split_path)
-                elif split_path[0] in categories:
-                    split_paths.remove(split_path)
-
-        return categories
-
-    def get_category(self, categories, path):
-        path_components = path.split("{")[0].strip('/').split('/')
-        for path_component in path_components:
-            if path_component in categories:
-                return path_component
-        return None
+    def get_category(self, path, method, callback, action):
+        """
+        Return a descriptive category string for the endpoint, eg. 'users'.
+
+        Examples of category/action pairs that should be generated for various
+        endpoints:
+
+        /users/                     [users][list], [users][create]
+        /users/{pk}/                [users][read], [users][update], [users][destroy]
+        /users/enabled/             [users][enabled]  (custom action)
+        /users/{pk}/star/           [users][star]     (custom action)
+        /users/{pk}/groups/         [groups][list], [groups][create]
+        /users/{pk}/groups/{pk}/    [groups][read], [groups][update], [groups][destroy]
+        """
+        path_components = path.strip('/').split('/')
+        path_components = [
+            component for component in path_components
+            if '{' not in component
+        ]
+        if action in self.known_actions:
+            # Default action, eg "/users/", "/users/{pk}/"
+            idx = -1
+        else:
+            # Custom action, eg "/users/{pk}/activate/", "/users/active/"
+            idx = -2
+
+        try:
+            return path_components[idx]
+        except IndexError:
+            return None
 
     # Methods for generating each individual `Link` instance...