diff --git a/mozilla/webtools/addons/public/htaccess.dist b/mozilla/webtools/addons/public/htaccess.dist
index c38cfb86376..eb4eeba8e9e 100644
--- a/mozilla/webtools/addons/public/htaccess.dist
+++ b/mozilla/webtools/addons/public/htaccess.dist
@@ -94,3 +94,8 @@ RewriteRule ^(\w+)/([\w-]+)[/]{0,1}$ $2.php?app=$1
 # Example:
 #    /firefox/ -> /?app=firefox
 RewriteRule ^(\w+)[/]{0,1}$ index.php?app=$1
+
+# Rewrite for client blocklist requests.
+# Example:
+#   /blocklist/1/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/1.5 -> blocklist.php?reqVersion=1&appGuid={ec8030f7-c20a-464f-9b0e-13a3a9e97384}&appVersion=1.5
+RewriteRule ^blocklist/(.+)/(.+)/(.+)[/]{0,1}$ blocklist.php?reqVersion=$1&appGuid=$2&appVersion=$3
diff --git a/mozilla/webtools/addons/public/htdocs/blocklist.php b/mozilla/webtools/addons/public/htdocs/blocklist.php
new file mode 100644
index 00000000000..faee244a40a
--- /dev/null
+++ b/mozilla/webtools/addons/public/htdocs/blocklist.php
@@ -0,0 +1,190 @@
+<?php
+/**
+ * This script tells clients whether or not a given add-on is blocklisted.
+ *
+ * It should always be well-formed and won't be seen by users,
+ * at least initially.
+ *
+ * At some point we should consider generating an XSLT in case we want to
+ * publish this list.
+ *
+ * @todo stylesheet for client viewing of blocklists
+ * @package amo 
+ * @subpackage pub
+ */
+startProcessing('blocklist.tpl', $memcacheId, $compileId, 'xml');
+
+
+
+/**
+ *  VARIABLES
+ *
+ *  Initialize, set up and clean variables.
+ */
+
+// Required variables that we need to run the script.
+$required_vars = array('reqVersion',    // Used as a marker for the current URI scheme, in case it changes later.
+                       'appGuid',       // GUID of the client requesting the blocklist.
+                       'appVersion');   // Version of the client requesting the blocklist (not used).
+
+// Debug flag.
+$debug = (isset($_GET['debug']) && $_GET['debug'] == 'true') ? true : false;
+
+// Array to hold errors for debugging.
+$errors = array();
+
+// Iterate through required variables, and escape/assign them as necessary.
+foreach ($required_vars as $var) {
+    if (empty($_GET[$var])) {
+        $errors[] = 'Required variable '.$var.' not set.'; // set debug error
+    }
+}
+
+
+
+// If we have all of our data, clean it up for our queries.
+if (empty($errors)) {
+
+    // We will need our DB in order to perform our query.
+    require_once('includes.php');
+
+    // Iterate through required variables, and escape/assign them as necessary.
+    foreach ($required_vars as $var) {
+        $sql[$var] = mysql_real_escape_string($_GET[$var]);
+    }
+
+
+
+    /*
+     *  QUERIES  
+     *  
+     *  All of our variables are cleaned.
+     *  Now attempt to retrieve blocklist information for this application.
+     */ 
+    $query = "
+        SELECT 
+            blitems.id as itemId,
+            blitems.guid as itemGuid,
+            blitems.min as itemMin,
+            blitems.max as itemMax,
+            blapps.id as appId,
+            blapps.item_id as appItemId,
+            blapps.guid as appGuid,
+            blapps.min as appMin,
+            blapps.max as appMax
+        FROM 
+            blitems
+        LEFT JOIN blapps on blitems.id = blapps.item_id
+        WHERE
+            blapps.guid = '{$sql['appGuid']}'
+            OR blapps.guid IS NULL
+        ORDER BY
+            itemGuid, appGuid, itemMin, appMin
+    ";
+
+    $db->query($query, SQL_ALL, SQL_ASSOC);
+
+    if (DB::isError($db->record)) {
+        $errors[] = 'MySQL query for blocklist failed.'; 
+    } elseif (empty($db->record)) {
+        $errors[] = 'No matching blocklist for given application GUID.'; 
+    } else {
+        $blocklist = array();
+
+        foreach ($db->record as $row) {
+
+            // If we have item itemMin/itemMax values or an appId possible ranges, we create
+            // hashes for each itemId and its related range.
+            // 
+            // Since itemGuids can have different itemIds, they are the first hash.  Each
+            // itemId is effectively an item's versionRange.  For each one of these we create
+            // a corresponding array containing the range values, which could be NULL.
+            if (!empty($row['itemMin']) && !empty($row['itemMax']) || !empty($row['appItemId'])) {
+                $blocklist['items'][$row['itemGuid']][$row['itemId']] = array(
+                    'itemMin' => $row['itemMin'],
+                    'itemMax' => $row['itemMax']
+                );
+
+            // Otherwise, our items array only contains a top-level containing the itemGuid.
+            //
+            // Doing so tells our template to terminate the item with /> because there is
+            // nothing left to display.
+            } else {
+                $blocklist['items'][$row['itemGuid']] = null;
+            }
+
+            // If we retrieved non-null blapp data, store it in the apps array.
+            //
+            // These are referenced later by their foreign key relationship to items (appItemId).
+            if ($row['appItemId']) {
+                $blocklist['apps'][$row['itemGuid']][$row['appItemId']][$row['appGuid']][] = array(
+                    'appMin' => $row['appMin'],
+                    'appMax' => $row['appMax']
+                );
+            }
+        }
+        
+        // Send our array to the template.
+        $tpl->assign('blocklist',$blocklist);
+    }
+} 
+
+
+
+/*
+ *  DEBUG
+ *
+ *  If we get here, something went wrong.  For testing purposes, we can
+ *  optionally display errers based on $_GET['debug'].
+ *
+ *  By default, no errors are ever displayed because humans do not read this
+ *  script.
+ *
+ *  Until there is some sort of API for how clients handle errors, 
+ *  things should remain this way.
+ */
+if ($debug == true) {
+    echo '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">';
+    echo '<html lang="en">';
+
+    echo '<head>';
+    echo '<title>blocklist.php Debug Information</title>';
+    echo '<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">';
+    echo '</head>';
+
+    echo '<body>';
+
+    echo '<h1>Parameters</h1>';
+    echo '<pre>';
+    print_r($_GET);
+    echo '</pre>';
+
+    if (!empty($query)) {
+        echo '<h1>Query</h1>';
+        echo '<pre>';
+        echo $query;
+        echo '</pre>';
+    }
+
+    if (!empty($blocklist)) {
+        echo '<h1>Result</h1>';
+        echo '<pre>';
+        print_r($blocklist);
+        echo '</pre>';
+    }
+
+    if (!empty($errors) && is_array($errors)) {
+        echo '<h1>Errors Found</h1>';
+        echo '<pre>';
+        print_r($errors);
+        echo '</pre>';
+    } else {
+        echo '<h1>No Errors Found</h1>';
+    }
+
+    echo '</body>';
+
+    echo '</html>';
+    exit;
+}
+?>
diff --git a/mozilla/webtools/addons/public/tpl/blocklist.tpl b/mozilla/webtools/addons/public/tpl/blocklist.tpl
new file mode 100644
index 00000000000..7b604997290
--- /dev/null
+++ b/mozilla/webtools/addons/public/tpl/blocklist.tpl
@@ -0,0 +1,32 @@
+<?xml version="1.0"?>
+<blocklist xmlns="http://www.mozilla.org/2006/addons-blocklist">
+{if $blocklist}
+  <emItems>
+{   foreach key=itemGuid item=item from=$blocklist.items}
+{       if $item}
+    <emItem id="{$itemGuid|escape:html:"UTF-8"}">
+{           foreach key=itemId item=itemRange from=$item}
+{               if $blocklist.apps.$itemGuid.$itemId}
+      <versionRange{if $itemRange.itemMin and $itemRange.itemMax} minVersion="{$itemRange.itemMin|escape:html:"UTF-8"}" maxVersion="{$itemRange.itemMax|escape:html:"UTF-8"}"{/if}>
+{                   foreach key=appGuid item=app from=$blocklist.apps.$itemGuid.$itemId}
+        <targetApplication{if $appGuid} id="{$appGuid|escape:html:"UTF-8"}"{/if}>
+{                       foreach item=appRange from=$app}
+{                           if $appRange.appMin and $appRange.appMax}
+          <versionRange minVersion="{$appRange.appMin|escape:html:"UTF-8"}" maxVersion="{$appRange.appMax|escape:html:"UTF-8"}"/>
+{                           /if}
+{                       /foreach}
+        </targetApplication>
+{                   /foreach}
+      </versionRange>
+{               else}
+      <versionRange minVersion="{$itemRange.itemMin|escape:html:"UTF-8"}" maxVersion="{$itemRange.itemMax|escape:html:"UTF-8"}"/>
+{               /if}
+{           /foreach}
+    </emItem>
+{       else}
+    <emItem id="{$itemGuid|escape:html:"UTF-8"}"/>
+{       /if}
+{   /foreach}
+  </emItems>
+{/if}
+</blocklist>