diff --git a/ansible_mitogen/connection.py b/ansible_mitogen/connection.py
index 59e82695..e71a98c3 100644
--- a/ansible_mitogen/connection.py
+++ b/ansible_mitogen/connection.py
@@ -131,6 +131,20 @@ def _connect_setns(spec):
     }
 
 
+def _connect_su(spec):
+    return {
+        'method': 'su',
+        'enable_lru': True,
+        'kwargs': {
+            'username': spec['become_user'],
+            'password': spec['become_pass'],
+            'python_path': spec['python_path'],
+            'su_path': spec['become_exe'],
+            'connect_timeout': spec['timeout'],
+        }
+    }
+
+
 def _connect_sudo(spec):
     return {
         'method': 'sudo',
@@ -146,6 +160,20 @@ def _connect_sudo(spec):
     }
 
 
+def _connect_mitogen_su(spec):
+    # su as a first-class proxied connection, not a become method.
+    return {
+        'method': 'su',
+        'kwargs': {
+            'username': spec['remote_user'],
+            'password': spec['password'],
+            'python_path': spec['python_path'],
+            'su_path': spec['become_exe'],
+            'connect_timeout': spec['timeout'],
+        }
+    }
+
+
 def _connect_mitogen_sudo(spec):
     # sudo as a first-class proxied connection, not a become method.
     return {
@@ -170,7 +198,9 @@ CONNECTION_METHOD = {
     'machinectl': _connect_machinectl,
     'setns': _connect_setns,
     'ssh': _connect_ssh,
+    'su': _connect_su,
     'sudo': _connect_sudo,
+    'mitogen_su': _connect_mitogen_su,
     'mitogen_sudo': _connect_mitogen_sudo,
 }
 
@@ -266,8 +296,8 @@ class Connection(ansible.plugins.connection.ConnectionBase):
     #: target machine (i.e. via sudo).
     context = None
 
-    #: Only sudo is supported for now.
-    become_methods = ['sudo']
+    #: Only sudo and su are supported for now.
+    become_methods = ['sudo', 'su']
 
     #: Set to 'ansible_python_interpreter' by on_action_run().
     python_path = None
diff --git a/docs/ansible.rst b/docs/ansible.rst
index 893cdad4..9e03b190 100644
--- a/docs/ansible.rst
+++ b/docs/ansible.rst
@@ -110,11 +110,10 @@ Installation
 Noteworthy Differences
 ----------------------
 
-* Ansible 2.3, 2.4 and 2.5 are supported. File bugs to register interest in
-  older releases.
+* Ansible 2.3, 2.4 and 2.5 are supported on Python 2.7.
 
-* The ``sudo`` become method is available and ``su`` is planned. File bugs to
-  register interest in additional methods.
+* The ``su`` and ``sudo`` become methods are available. File bugs to register
+  interest in more.
 
 * The `docker <https://docs.ansible.com/ansible/2.5/plugins/connection/docker.html>`_,
   `jail <https://docs.ansible.com/ansible/2.5/plugins/connection/jail.html>`_,
@@ -123,8 +122,9 @@ Noteworthy Differences
   `lxd <https://docs.ansible.com/ansible/2.5/plugins/connection/lxd.html>`_,
   and `ssh <https://docs.ansible.com/ansible/2.5/plugins/connection/ssh.html>`_
   built-in connection types are supported, along with Mitogen-specific
-  :ref:`machinectl <machinectl>`, :ref:`mitogen_sudo <sudo>`, and
-  :ref:`setns <setns>` types. File bugs to register interest in others.
+  :ref:`machinectl <machinectl>`, :ref:`mitogen_su <su>`, :ref:`mitogen_sudo
+  <sudo>`, and :ref:`setns <setns>` types. File bugs to register interest in
+  others.
 
 * Local commands execute in a reuseable interpreter created identically to
   interpreters on targets. Presently one interpreter per ``become_user``
@@ -558,6 +558,31 @@ process.
   as ``/bin/machinectl``.
 
 
+.. _su:
+
+Su
+~~
+
+Su can be used as a connection method that supports connection delegation, or
+as a become method.
+
+When used as a become method:
+
+* ``ansible_python_interpreter``
+* ``ansible_su_exe``, ``ansible_become_exe``
+* ``ansible_su_user``, ``ansible_become_user`` (default: ``root``)
+* ``ansible_su_pass``, ``ansible_become_pass`` (default: assume passwordless)
+* ``su_flags``, ``become_flags``
+* ansible.cfg: ``timeout``
+
+When used as the ``mitogen_su`` connection method:
+
+* The inventory hostname has no special meaning.
+* ``ansible_user``: username to su as.
+* ``ansible_password``: password to su as.
+* ``ansible_python_interpreter``
+
+
 .. _sudo:
 
 Sudo