diff --git a/doc/source/using-sessions.rst b/doc/source/using-sessions.rst
index 1daddaf5..ffd140f1 100644
--- a/doc/source/using-sessions.rst
+++ b/doc/source/using-sessions.rst
@@ -375,14 +375,64 @@ the ``microversion`` parameter of the `request` method on the
 to pass the appropriate header to the service informing the service of the
 microversion the user wants.
 
+.. code-block:: python
+
+    resp = session.get('/volumes',
+                       microversion='3.15',
+                       endpoint_filter={'service_type': 'volume',
+                                        'interface': 'public',
+                                        'min_version': '3',
+                                        'max_version': 'latest'})
+
 If the user is using a :class:`keystoneauth1.adapter.Adapter`, the
 `service_type`, which is a part of the data sent in the microversion header,
 will be taken from the Adapter's `service_type`.
 
+.. code-block:: python
+
+    adapter = keystoneauth1.adapter.Adapter(
+        session=session,
+        service_type='compute',
+        interface='public',
+        min_version='2.1')
+    response = adapter.get('/servers', microversion='2.38')
+
+The user can also provide a ``default_microversion`` parameter to the Adapter
+constructor which will be used on all requests where an explicit microversion
+is not requested.
+
+.. code-block:: python
+
+    adapter = keystoneauth1.adapter.Adapter(
+        session=session,
+        service_type='compute',
+        interface='public',
+        min_version='2.1',
+        default_microversion='2.38')
+    response = adapter.get('/servers')
+
 If the user is using a :class:`keystoneauth1.session.Session`, the
-`service_type` will be taken from the `service_type` in `endpoint_filter`
-or alternately from the parameter `microversion_service_type` in case there
-is no `service_type` in `endpoint_filter` for some reason.
+`service_type` will be taken from the `service_type` in `endpoint_filter`.
+
+If the `service_type` is the incorrect value to use for the microversion header
+for the service in question, the parameter `microversion_service_type` can be
+given. For instance, although keystoneauth already knows about Cinder, the
+`service_type` for Cinder is ``block-storage`` but the microversion header
+expects ``volume``.
+
+.. code-block:: python
+
+    # Interactions with cinder do not need to explicitly override the
+    # microversion_service_type - it is only being used as an example for the
+    # use of the parameter.
+    resp = session.get('/volumes',
+                       microversion='3.15',
+                       microversion_service_type='volume',
+                       endpoint_filter={'service_type': 'block-storage',
+                                        'interface': 'public',
+                                        'min_version': '3',
+                                        'max_version': 'latest'})
+
 
 .. _API-WG Specs: http://specs.openstack.org/openstack/api-wg/
 .. _Consuming the Catalog: http://specs.openstack.org/openstack/api-wg/guidelines/consuming-catalog.html
diff --git a/keystoneauth1/session.py b/keystoneauth1/session.py
index bef5d566..c35182d1 100644
--- a/keystoneauth1/session.py
+++ b/keystoneauth1/session.py
@@ -444,7 +444,7 @@ class Session(object):
                     " service_type information is available. Either provide a"
                     " service_type in endpoint_filter or pass"
                     " microversion_service_type as an argument.".format(
-                        microversion=discover.version_to_string(microversion)))
+                        microversion=microversion))
 
         # TODO(mordred) cinder uses volume in its microversion header. This
         # logic should be handled in the future by os-service-types but for
@@ -452,17 +452,13 @@ class Session(object):
         if (service_type.startswith('volume')
                 or service_type == 'block-storage'):
             service_type = 'volume'
-        # TODO(mordred) Fix this as part of the service-types generalized
-        # fix. Ironic does not yet support the new version header
-        if service_type != 'baremetal':
-            headers.setdefault('OpenStack-API-Version',
-                               '{service_type} {microversion}'.format(
-                                   service_type=service_type,
-                                   microversion=microversion))
+        headers.setdefault('OpenStack-API-Version',
+                           '{service_type} {microversion}'.format(
+                               service_type=service_type,
+                               microversion=microversion))
         header_names = _mv_legacy_headers_for_service(service_type)
         for h in header_names:
             headers.setdefault(h, microversion)
-        return headers
 
     @positional()
     def request(self, url, method, json=None, original_ip=None,
@@ -546,10 +542,10 @@ class Session(object):
         :param str microversion_service_type: The service_type to be sent in
                        the microversion header, if a microversion is given.
                        Defaults to the value of service_type from
-                       endpoint_filter if one exists. If endpoint_filter
-                       does not have a service_type, microversion is given and
-                       microversion_service_type is not provided, an exception
-                       will be raised.
+                       endpoint_filter if one exists. If endpoint_filter is not
+                       provided or does not have a service_type, microversion
+                       is given and microversion_service_type is not provided,
+                       an exception will be raised.
         :param kwargs: any other parameter that can be passed to
                        :meth:`requests.Session.request` (such as `headers`).
                        Except:
diff --git a/keystoneauth1/tests/unit/test_session.py b/keystoneauth1/tests/unit/test_session.py
index 1a6a9577..cba898bf 100644
--- a/keystoneauth1/tests/unit/test_session.py
+++ b/keystoneauth1/tests/unit/test_session.py
@@ -127,8 +127,9 @@ class SessionTests(utils.TestCase):
         headers = {}
         client_session.Session._set_microversion_headers(
             headers, '2.30', 'baremetal', None)
+        self.assertEqual(headers['OpenStack-API-Version'], 'baremetal 2.30')
         self.assertEqual(headers['X-OpenStack-Ironic-API-Version'], '2.30')
-        self.assertEqual(len(headers.keys()), 1)
+        self.assertEqual(len(headers.keys()), 2)
 
         # volumev2 service-type - volume microversion
         headers = {}
@@ -183,6 +184,7 @@ class SessionTests(utils.TestCase):
 
         self.assertTrue(resp.ok)
         self.assertRequestHeaderEqual('OpenStack-API-Version', 'compute 2.30')
+        self.assertRequestHeaderEqual('X-OpenStack-Nova-API-Version', '2.30')
 
     def test_user_agent(self):
         session = client_session.Session()
diff --git a/releasenotes/notes/microversion-header-support-901acd820a21d788.yaml b/releasenotes/notes/microversion-header-support-901acd820a21d788.yaml
new file mode 100644
index 00000000..3f841f36
--- /dev/null
+++ b/releasenotes/notes/microversion-header-support-901acd820a21d788.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - Added support for specifying a microversion to use on
+    a given REST request. The microversion can be specified
+    on session request calls and a default can be set on
+    Adapter construction.