diff --git a/gunicorn/config.py b/gunicorn/config.py
index af63407c..0558530c 100644
--- a/gunicorn/config.py
+++ b/gunicorn/config.py
@@ -987,6 +987,23 @@ class Umask(Setting):
         """
 
 
+class Initgroups(Setting):
+    name = "initgroups"
+    section = "Server Mechanics"
+    cli = ["--initgroups"]
+    validator = validate_bool
+    action = 'store_true'
+    default = False
+
+    desc = """\
+        If true, set the worker process's group access list with all of the
+        groups of which the specified username is a member, plus the specified
+        group id.
+
+        .. versionadded:: 19.7
+        """
+
+
 class TmpUploadDir(Setting):
     name = "tmp_upload_dir"
     section = "Server Mechanics"
diff --git a/gunicorn/util.py b/gunicorn/util.py
index 64c5ff57..a011fb85 100644
--- a/gunicorn/util.py
+++ b/gunicorn/util.py
@@ -54,6 +54,7 @@ hop_headers = set("""
 
 try:
     from setproctitle import setproctitle
+
     def _setproctitle(title):
         setproctitle("gunicorn: %s" % title)
 except ImportError:
@@ -147,13 +148,30 @@ def load_class(uri, default="gunicorn.workers.sync.SyncWorker",
         return getattr(mod, klass)
 
 
-def set_owner_process(uid, gid):
+def get_username(uid):
+    """ get the username for a user id"""
+    return pwd.getpwuid(uid).pw_name
+
+
+def set_owner_process(uid, gid, initgroups=False):
     """ set user and group of workers processes """
+
     if gid:
+        if uid:
+            try:
+                username = get_username(uid)
+            except KeyError:
+                initgroups = False
+
         # versions of python < 2.6.2 don't manage unsigned int for
         # groups like on osx or fedora
         gid = abs(gid) & 0x7FFFFFFF
-        os.setgid(gid)
+
+        if initgroups:
+            os.initgroups(username, gid)
+        else:
+            os.setgid(gid)
+
     if uid:
         os.setuid(uid)
 
diff --git a/gunicorn/workers/base.py b/gunicorn/workers/base.py
index c00101df..4ceb691b 100644
--- a/gunicorn/workers/base.py
+++ b/gunicorn/workers/base.py
@@ -102,7 +102,8 @@ class Worker(object):
             for k, v in self.cfg.env.items():
                 os.environ[k] = v
 
-        util.set_owner_process(self.cfg.uid, self.cfg.gid)
+        util.set_owner_process(self.cfg.uid, self.cfg.gid,
+                               initgroups=self.cfg.initgroups)
 
         # Reseed the random number generator
         util.seed()