diff --git a/syncano/models/accounts.py b/syncano/models/accounts.py
index aa07d50..16639d2 100644
--- a/syncano/models/accounts.py
+++ b/syncano/models/accounts.py
@@ -156,10 +156,24 @@ def auth(self, username=None, password=None):
     def _user_groups_method(self, group_id=None, method='GET'):
         properties = self.get_endpoint_data()
         endpoint = self._meta.resolve_endpoint('groups', properties)
-        if group_id is not None:
+
+        if group_id is not None and method != 'POST':
             endpoint += '{}/'.format(group_id)
         connection = self._get_connection()
-        return connection.request(method, endpoint)
+
+        data = {}
+        if method == 'POST':
+            data = {'group': group_id}
+
+        response = connection.request(method, endpoint, data=data)
+
+        if method == 'DELETE':  # no response here;
+            return
+
+        if 'objects' in response:
+            return [Group(**group_response['group']) for group_response in response['objects']]
+
+        return Group(**response['group'])
 
     def add_to_group(self, group_id):
         return self._user_groups_method(group_id, method='POST')
@@ -212,17 +226,28 @@ class Meta:
     def _group_users_method(self, user_id=None, method='GET'):
         properties = self.get_endpoint_data()
         endpoint = self._meta.resolve_endpoint('users', properties)
-        if user_id is not None:
+        if user_id is not None and method != 'POST':
             endpoint += '{}/'.format(user_id)
         connection = self._get_connection()
+
+        data = {}
+        if method == 'POST':
+            data = {'user': user_id}
+
         try:
-            response = connection.request(method, endpoint)
+            response = connection.request(method, endpoint, data=data)
         except SyncanoRequestError as e:
             if e.status_code == 404:
                 raise UserNotFound(e.status_code, 'User not found.')
             raise
 
-        return response
+        if method == 'DELETE':
+            return
+
+        if 'objects' in response:
+            return [User(**user_response['user']) for user_response in response['objects']]
+
+        return User(**response['user'])
 
     def list_users(self):
         return self._group_users_method()
diff --git a/tests/integration_test_user.py b/tests/integration_test_user.py
index 87fc9d5..e314e28 100644
--- a/tests/integration_test_user.py
+++ b/tests/integration_test_user.py
@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 from syncano.exceptions import UserNotFound
-from syncano.models import User
+from syncano.models import Group, User
 from tests.integration_test import InstanceMixin, IntegrationTest
 
 
@@ -62,3 +62,55 @@ def setUpClass(cls):
     def test_if_custom_error_is_raised_on_user_group(self):
         with self.assertRaises(UserNotFound):
             self.group.user_details(user_id=221)
+
+    def test_user_group_membership(self):
+        user = User.please.create(
+            username='testa',
+            password='1234'
+        )
+
+        group_test = Group.please.create(label='new_group_a')
+
+        groups = user.list_groups()
+        self.assertListEqual(groups, [])
+
+        group = user.add_to_group(group_id=group_test.id)
+        self.assertEqual(group.id, group_test.id)
+        self.assertEqual(group.label, group_test.label)
+
+        groups = user.list_groups()
+        self.assertEqual(len(groups), 1)
+        self.assertEqual(groups[0].id, group_test.id)
+
+        group = user.group_details(group_id=group_test.id)
+        self.assertEqual(group.id, group_test.id)
+        self.assertEqual(group.label, group_test.label)
+
+        response = user.remove_from_group(group_id=group_test.id)
+        self.assertIsNone(response)
+
+    def test_group_user_membership(self):
+        user_test = User.please.create(
+            username='testb',
+            password='1234'
+        )
+
+        group = Group.please.create(label='new_group_b')
+
+        users = group.list_users()
+        self.assertListEqual(users, [])
+
+        user = group.add_user(user_id=user_test.id)
+        self.assertEqual(user.id, user_test.id)
+        self.assertEqual(user.username, user_test.username)
+
+        users = group.list_users()
+        self.assertEqual(len(users), 1)
+        self.assertEqual(users[0].id, user_test.id)
+
+        user = group.user_details(user_id=user_test.id)
+        self.assertEqual(user.id, user_test.id)
+        self.assertEqual(user.username, user_test.username)
+
+        response = group.delete_user(user_id=user_test.id)
+        self.assertIsNone(response)