diff --git a/src/applications/auth/provider/PhabricatorAuthProviderOAuth1MediaWiki.php b/src/applications/auth/provider/PhabricatorAuthProviderOAuth1MediaWiki.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/provider/PhabricatorAuthProviderOAuth1MediaWiki.php
@@ -0,0 +1,103 @@
+<?php
+
+final class PhabricatorAuthProviderOAuth1MediaWiki
+  extends PhabricatorAuthProviderOAuth1 {
+
+  public function getProviderName() {
+    return pht('MediaWiki');
+  }
+
+  protected function getProviderConfigurationHelp() {
+    $login_uri = PhabricatorEnv::getURI($this->getLoginURI());
+
+    return pht(
+      "To configure MediaWiki OAuth, create a new application here:".
+      "\n\n".
+      "https://www.mediawiki.org/wiki/Special:OAuthConsumerRegistration/propose".
+      "\n\n".
+      "When creating your application, use these settings:".
+      "\n\n".
+      "  - **Callback URL:** Set this to: `%s`".
+      "\n\n".
+      "After completing configuration, copy the **Consumer Key** and ".
+      "**Consumer Secret** to the fields above.",
+      $login_uri);
+  }
+
+  protected function newOAuthAdapter() {
+    return new PhutilAuthAdapterOAuthMediaWiki();
+  }
+
+  protected function getLoginIcon() {
+    return 'MediaWiki';
+  }
+
+  public function processLoginRequest(
+    PhabricatorAuthLoginController $controller) {
+
+    $request = $controller->getRequest();
+    $adapter = $this->getAdapter();
+    $account = null;
+    $response = null;
+
+    if ($request->isHTTPPost()) {
+      $callback_uri = $adapter->getCallbackURI();
+      $adapter->setCallbackURI($callback_uri);
+      $uri = $adapter->getClientRedirectURI();
+      $response = id(new AphrontRedirectResponse())->setURI($uri);
+      return array($account, $response);
+    }
+
+    $denied = $request->getStr('denied');
+    if (strlen($denied)) {
+      // Twitter indicates that the user cancelled the login attempt by
+      // returning "denied" as a parameter.
+      throw new PhutilAuthUserAbortedException();
+    }
+
+    // NOTE: You can get here via GET, this should probably be a bit more
+    // user friendly.
+
+    $token = $request->getStr('oauth_token');
+    $verifier = $request->getStr('oauth_verifier');
+
+    if (!$token) {
+      throw new Exception("Expected 'oauth_token' in request!");
+    }
+
+    if (!$verifier) {
+      throw new Exception("Expected 'oauth_verifier' in request!");
+    }
+
+    list ( $ctok, $csec ) = explode(':', $_COOKIE['mwoauth'], 2);
+    if ($ctok !== $token) {
+      throw new Exception("Token from callback doesn't match your cookie.");
+    }
+
+    $adapter->setToken($token);
+    $adapter->setTokenSecret($csec);
+    $adapter->setVerifier($verifier);
+
+    // NOTE: As a side effect, this will cause the OAuth adapter to request
+    // an access token.
+
+    try {
+      $account_id = $adapter->getAccountID();
+    } catch (Exception $ex) {
+        throw $ex;
+    }
+
+    if (!strlen($account_id)) {
+      $response = $controller->buildProviderErrorResponse(
+        $this,
+        pht(
+          'The OAuth provider failed to retrieve an account ID.'));
+
+      return array($account, $response);
+    }
+
+    return array($this->loadOrCreateAccount($account_id), $response);
+  }
+
+
+}