--- a/services/sync/modules/telemetry.js
+++ b/services/sync/modules/telemetry.js
@@ -21,16 +21,18 @@ Cu.import("resource://services-common/as
 
 let constants = {};
 Cu.import("resource://services-sync/constants.js", constants);
 
 XPCOMUtils.defineLazyModuleGetter(this, "TelemetryController",
                               "resource://gre/modules/TelemetryController.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "TelemetryUtils",
                                   "resource://gre/modules/TelemetryUtils.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "TelemetryEnvironment",
+                                  "resource://gre/modules/TelemetryEnvironment.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "OS",
                                   "resource://gre/modules/osfile.jsm");
 
 XPCOMUtils.defineLazyServiceGetter(this, "Telemetry",
                                    "@mozilla.org/base/telemetry;1",
                                    "nsITelemetry");
 
 const log = Log.repository.getLogger("Sync.Telemetry");
@@ -421,16 +423,17 @@ class SyncTelemetryImpl {
     this.lastDeviceID = undefined;
     let sessionStartDate = Services.startup.getStartupInfo().main;
     this.sessionStartDate = TelemetryUtils.toLocalTimeISOString(
       TelemetryUtils.truncateToHours(sessionStartDate));
   }
 
   getPingJSON(reason) {
     return {
+      os: TelemetryEnvironment.currentEnvironment["system"]["os"],
       why: reason,
       discarded: this.discarded || undefined,
       version: PING_FORMAT_VERSION,
       syncs: this.payloads.slice(),
       uid: this.lastUID,
       deviceID: this.lastDeviceID,
       sessionStartDate: this.sessionStartDate,
       events: this.events.length == 0 ? undefined : this.events,

--- a/services/sync/tests/unit/sync_ping_schema.json
+++ b/services/sync/tests/unit/sync_ping_schema.json
@@ -1,16 +1,17 @@
 {
   "$schema": "http://json-schema.org/draft-04/schema#",
   "description": "schema for Sync pings, documentation avaliable in toolkit/components/telemetry/docs/sync-ping.rst",
   "type": "object",
   "additionalProperties": false,
   "required": ["version", "syncs", "why", "uid"],
   "properties": {
     "version": { "type": "integer", "minimum": 0 },
+    "os": { "type": "object" },
     "discarded": { "type": "integer", "minimum": 1 },
     "why": { "enum": ["shutdown", "schedule", "idchange"] },
     "uid": {
       "type": "string",
       "pattern": "^[0-9a-f]{32}$"
     },
     "deviceID": {
       "type": "string",

--- a/services/sync/tests/unit/test_telemetry.js
+++ b/services/sync/tests/unit/test_telemetry.js
@@ -85,17 +85,24 @@ add_task(async function test_basic() {
 
   for (let coll of collections) {
     handlers["/1.1/johndoe/storage/" + coll] = upd(coll, new ServerCollection({}, true).handler());
   }
 
   let server = httpd_setup(handlers);
   await configureIdentity({ username: "johndoe" }, server);
 
-  await sync_and_validate_telem(true);
+  let ping = await sync_and_validate_telem(true, true);
+
+  // Check the "os" block - we can't really check specific values, but can
+  // check it smells sane.
+  ok(ping.os, "there is an OS block");
+  ok("name" in ping.os, "there is an OS name");
+  ok("version" in ping.os, "there is an OS version");
+  ok("locale" in ping.os, "there is an OS locale");
 
   Svc.Prefs.resetBranch("");
   await promiseStopServer(server);
 });
 
 add_task(async function test_processIncoming_error() {
   let engine = new BookmarksEngine(Service);
   let store  = engine._store;

--- a/toolkit/components/telemetry/docs/data/sync-ping.rst
+++ b/toolkit/components/telemetry/docs/data/sync-ping.rst
@@ -13,16 +13,17 @@ Structure:
 .. code-block:: js
 
     {
       version: 4,
       type: "sync",
       ... common ping data
       payload: {
         version: 1,
+        os : { ... }, // os data from the current telemetry environment. OS specific, but typically includes name, version and locale.
         discarded: <integer count> // Number of syncs discarded -- left out if zero.
         why: <string>, // Why did we submit the ping? Either "shutdown", "schedule", or "idchanged".
         uid: <string>, // Hashed FxA unique ID, or string of 32 zeros. If this changes between syncs, the payload is submitted.
         deviceID: <string>, // Hashed FxA Device ID, hex string of 64 characters, not included if the user is not logged in. If this changes between syncs, the payload is submitted.
         sessionStartDate: <ISO date>, // hourly precision, ISO date in local time
         // Array of recorded syncs. The ping is not submitted if this would be empty
         syncs: [{
           when: <integer milliseconds since epoch>,