diff --git a/DOCUMENTATION.md b/DOCUMENTATION.md
index b9c4c572..8718c08f 100644
--- a/DOCUMENTATION.md
+++ b/DOCUMENTATION.md
@@ -829,6 +829,10 @@ Available backends:
 `oauth2`
 : Use an OAuth2 server to authenticate users.
 
+`pam`
+: Use local PAM to authenticate users.
+
+
 Default: `none`
 
 ##### cache_logins
diff --git a/radicale/auth/pam.py b/radicale/auth/pam.py
new file mode 100644
index 00000000..25e66b19
--- /dev/null
+++ b/radicale/auth/pam.py
@@ -0,0 +1,93 @@
+# -*- coding: utf-8 -*-
+#
+# This file is part of Radicale Server - Calendar Server
+# Copyright © 2011 Henry-Nicolas Tourneur
+#
+# This library is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Radicale.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+PAM authentication.
+
+Authentication based on the ``pam-python`` module.
+
+"""
+
+import grp
+import pam
+import pwd
+
+from .. import config, log
+
+
+GROUP_MEMBERSHIP = config.get("auth", "pam_group_membership")
+
+
+# Compatibility for old versions of python-pam.
+if hasattr(pam, "pam"):
+    def pam_authenticate(*args, **kwargs):
+        return pam.pam().authenticate(*args, **kwargs)
+else:
+    def pam_authenticate(*args, **kwargs):
+        return pam.authenticate(*args, **kwargs)
+
+
+def is_authenticated(user, password):
+    """Check if ``user``/``password`` couple is valid."""
+    if user is None or password is None:
+        return False
+
+    # Check whether the user exists in the PAM system
+    try:
+        pwd.getpwnam(user).pw_uid
+    except KeyError:
+        log.LOGGER.debug("User %s not found" % user)
+        return False
+    else:
+        log.LOGGER.debug("User %s found" % user)
+
+    # Check whether the group exists
+    try:
+        # Obtain supplementary groups
+        members = grp.getgrnam(GROUP_MEMBERSHIP).gr_mem
+    except KeyError:
+        log.LOGGER.debug(
+            "The PAM membership required group (%s) doesn't exist" %
+            GROUP_MEMBERSHIP)
+        return False
+
+    # Check whether the user exists
+    try:
+        # Get user primary group
+        primary_group = grp.getgrgid(pwd.getpwnam(user).pw_gid).gr_name
+    except KeyError:
+        log.LOGGER.debug("The PAM user (%s) doesn't exist" % user)
+        return False
+
+    # Check whether the user belongs to the required group
+    # (primary or supplementary)
+    if primary_group == GROUP_MEMBERSHIP or user in members:
+        log.LOGGER.debug(
+            "The PAM user belongs to the required group (%s)" %
+            GROUP_MEMBERSHIP)
+        # Check the password
+        if pam_authenticate(user, password, service='radicale'):
+            return True
+        else:
+            log.LOGGER.debug("Wrong PAM password")
+    else:
+        log.LOGGER.debug(
+            "The PAM user doesn't belong to the required group (%s)" %
+            GROUP_MEMBERSHIP)
+
+    return False