diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -7,7 +7,7 @@
  */
 return array(
   'names' => array(
-    'core.pkg.css' => 'aee99781',
+    'core.pkg.css' => 'ee3f9253',
     'core.pkg.js' => '1d376fa9',
     'darkconsole.pkg.js' => 'e7393ebb',
     'differential.pkg.css' => '3fb7f532',
@@ -163,7 +163,7 @@
     'rsrc/css/phui/workboards/phui-workboard.css' => 'bda3ef58',
     'rsrc/css/phui/workboards/phui-workcard.css' => '0c62d7c5',
     'rsrc/css/phui/workboards/phui-workpanel.css' => '92197373',
-    'rsrc/css/sprite-login.css' => '60e8560e',
+    'rsrc/css/sprite-login.css' => '6dbbbd97',
     'rsrc/css/sprite-tokens.css' => '9cdfd599',
     'rsrc/css/syntax/syntax-default.css' => '9923583c',
     'rsrc/externals/d3/d3.min.js' => 'a11a5ff2',
@@ -342,8 +342,8 @@
     'rsrc/image/phrequent_active.png' => 'a466a8ed',
     'rsrc/image/phrequent_inactive.png' => 'bfc15a69',
     'rsrc/image/resize.png' => 'fd476de4',
-    'rsrc/image/sprite-login-X2.png' => 'e3991e37',
-    'rsrc/image/sprite-login.png' => '03d5af29',
+    'rsrc/image/sprite-login-X2.png' => '4abee916',
+    'rsrc/image/sprite-login.png' => '2b9663fd',
     'rsrc/image/sprite-tokens-X2.png' => '804a5232',
     'rsrc/image/sprite-tokens.png' => 'b41d03da',
     'rsrc/image/texture/card-gradient.png' => '815f26e8',
@@ -890,7 +890,7 @@
     'releeph-request-differential-create-dialog' => '8d8b92cd',
     'releeph-request-typeahead-css' => '667a48ae',
     'setup-issue-css' => 'f794cfc3',
-    'sprite-login-css' => '60e8560e',
+    'sprite-login-css' => '6dbbbd97',
     'sprite-tokens-css' => '9cdfd599',
     'syntax-default-css' => '9923583c',
     'syntax-highlighting-css' => '769d3498',
diff --git a/resources/sprite/login_1x/Slack.png b/resources/sprite/login_1x/Slack.png
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
GIT binary patch
literal 0
Hc$@<O00001

literal 0
Hc$@<O00001

diff --git a/resources/sprite/login_2x/Slack.png b/resources/sprite/login_2x/Slack.png
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
GIT binary patch
literal 0
Hc$@<O00001

literal 0
Hc$@<O00001

diff --git a/resources/sprite/manifest/login.json b/resources/sprite/manifest/login.json
--- a/resources/sprite/manifest/login.json
+++ b/resources/sprite/manifest/login.json
@@ -91,6 +91,11 @@
       "rule": ".login-Phabricator",
       "hash": "d0f830803593bbcc025d7d5a29ee3ecd"
     },
+    "login-Slack": {
+      "name": "login-Slack",
+      "rule": ".login-Slack",
+      "hash": "fe0df2df040032b949aa05948b6bd986"
+    },
     "login-Stripe": {
       "name": "login-Stripe",
       "rule": ".login-Stripe",
diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -3587,6 +3587,7 @@
     'PhabricatorShowFiletreeSetting' => 'applications/settings/setting/PhabricatorShowFiletreeSetting.php',
     'PhabricatorSimpleEditType' => 'applications/transactions/edittype/PhabricatorSimpleEditType.php',
     'PhabricatorSite' => 'aphront/site/PhabricatorSite.php',
+    'PhabricatorSlackAuthProvider' => 'applications/auth/provider/PhabricatorSlackAuthProvider.php',
     'PhabricatorSlowvoteApplication' => 'applications/slowvote/application/PhabricatorSlowvoteApplication.php',
     'PhabricatorSlowvoteChoice' => 'applications/slowvote/storage/PhabricatorSlowvoteChoice.php',
     'PhabricatorSlowvoteCloseController' => 'applications/slowvote/controller/PhabricatorSlowvoteCloseController.php',
@@ -8590,6 +8591,7 @@
     'PhabricatorShowFiletreeSetting' => 'PhabricatorSelectSetting',
     'PhabricatorSimpleEditType' => 'PhabricatorEditType',
     'PhabricatorSite' => 'AphrontSite',
+    'PhabricatorSlackAuthProvider' => 'PhabricatorOAuth2AuthProvider',
     'PhabricatorSlowvoteApplication' => 'PhabricatorApplication',
     'PhabricatorSlowvoteChoice' => 'PhabricatorSlowvoteDAO',
     'PhabricatorSlowvoteCloseController' => 'PhabricatorSlowvoteController',
diff --git a/src/applications/auth/provider/PhabricatorSlackAuthProvider.php b/src/applications/auth/provider/PhabricatorSlackAuthProvider.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/provider/PhabricatorSlackAuthProvider.php
@@ -0,0 +1,36 @@
+<?php
+
+final class PhabricatorSlackAuthProvider
+  extends PhabricatorOAuth2AuthProvider {
+
+  public function getProviderName() {
+    return pht('Slack');
+  }
+
+  protected function getProviderConfigurationHelp() {
+    $login_uri = PhabricatorEnv::getURI($this->getLoginURI());
+
+    return pht(
+      "To configure Slack OAuth, create a new application here:".
+      "\n\n".
+      "https://api.slack.com/docs/sign-in-with-slack#create_slack_app".
+      "\n\n".
+      "When creating your application, use these settings:".
+      "\n\n".
+      "  - **Redirect URI:** Set this to: `%s`".
+      "\n\n".
+      "After completing configuration, copy the **Client ID** and ".
+      "**Client Secret** to the fields above. (You may need to generate the ".
+      "client secret by clicking 'New Secret' first.)",
+      $login_uri);
+  }
+
+  protected function newOAuthAdapter() {
+    return new PhutilSlackAuthAdapter();
+  }
+
+  protected function getLoginIcon() {
+    return 'Slack';
+  }
+
+}
diff --git a/webroot/rsrc/css/sprite-login.css b/webroot/rsrc/css/sprite-login.css
--- a/webroot/rsrc/css/sprite-login.css
+++ b/webroot/rsrc/css/sprite-login.css
@@ -14,7 +14,7 @@
 only screen and (min-resolution: 1.5dppx) {
   .sprite-login {
     background-image: url(/rsrc/image/sprite-login-X2.png);
-    background-size: 145px 145px;
+    background-size: 145px 174px;
   }
 }
 
@@ -91,30 +91,34 @@
   background-position: -58px -87px;
 }
 
-.login-Stripe {
+.login-Slack {
   background-position: -87px -87px;
 }
 
-.login-TestPayment {
+.login-Stripe {
   background-position: -116px -87px;
 }
 
-.login-TwitchTV {
+.login-TestPayment {
   background-position: 0px -116px;
 }
 
-.login-Twitter {
+.login-TwitchTV {
   background-position: -29px -116px;
 }
 
-.login-WePay {
+.login-Twitter {
   background-position: -58px -116px;
 }
 
-.login-WordPressCOM {
+.login-WePay {
   background-position: -87px -116px;
 }
 
-.login-Yahoo {
+.login-WordPressCOM {
   background-position: -116px -116px;
 }
+
+.login-Yahoo {
+  background-position: 0px -145px;
+}
diff --git a/webroot/rsrc/image/sprite-login-X2.png b/webroot/rsrc/image/sprite-login-X2.png
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
GIT binary patch
literal 0
Hc$@<O00001

literal 0
Hc$@<O00001

diff --git a/webroot/rsrc/image/sprite-login.png b/webroot/rsrc/image/sprite-login.png
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
GIT binary patch
literal 0
Hc$@<O00001

literal 0
Hc$@<O00001