--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -225,16 +225,17 @@ const listeners = {
     "RemoteLogins:findLogins": ["LoginManagerParent"],
     "RemoteLogins:findRecipes": ["LoginManagerParent"],
     "RemoteLogins:onFormSubmit": ["LoginManagerParent"],
     "RemoteLogins:autoCompleteLogins": ["LoginManagerParent"],
     "RemoteLogins:removeLogin": ["LoginManagerParent"],
     "RemoteLogins:insecureLoginFormPresent": ["LoginManagerParent"],
     // For Savant Shield study, bug 1465685. Study on desktop only.
     "LoginStats:LoginFillSuccessful": ["LoginManagerParent"],
+    "LoginStats:LoginEncountered": ["LoginManagerParent"],
     // PLEASE KEEP THIS LIST IN SYNC WITH THE MOBILE LISTENERS IN BrowserCLH.js
     "WCCR:registerProtocolHandler": ["Feeds"],
     "WCCR:registerContentHandler": ["Feeds"],
     "rtcpeer:CancelRequest": ["webrtcUI"],
     "rtcpeer:Request": ["webrtcUI"],
     "webrtc:CancelRequest": ["webrtcUI"],
     "webrtc:Request": ["webrtcUI"],
     "webrtc:StopRecording": ["webrtcUI"],

--- a/toolkit/components/passwordmgr/LoginManagerContent.jsm
+++ b/toolkit/components/passwordmgr/LoginManagerContent.jsm
@@ -433,18 +433,24 @@ var LoginManagerContent = {
    * Fetch logins from the parent for a given form and then attempt to fill it.
    *
    * @param {FormLike} form to fetch the logins for then try autofill.
    * @param {Window} window
    */
   _fetchLoginsFromParentAndFillForm(form, window) {
     this._detectInsecureFormLikes(window);
 
+    const isPrivateWindow = PrivateBrowsingUtils.isContentWindowPrivate(window);
+
     let messageManager = messageManagerFromWindow(window);
-    messageManager.sendAsyncMessage("LoginStats:LoginEncountered");
+    messageManager.sendAsyncMessage("LoginStats:LoginEncountered",
+                                    {
+                                      isPrivateWindow,
+                                      isPwmgrEnabled: gEnabled,
+                                    });
 
     if (!gEnabled) {
       return;
     }
 
     this._getLoginDataFromParent(form, { showMasterPassword: true })
         .then(this.loginsFound.bind(this))
         .catch(Cu.reportError);

--- a/toolkit/components/passwordmgr/LoginManagerParent.jsm
+++ b/toolkit/components/passwordmgr/LoginManagerParent.jsm
@@ -89,16 +89,23 @@ var LoginManagerParent = {
         // TODO Verify msg.target's principals against the formOrigin?
         this.onFormSubmit(data.hostname,
                           data.formSubmitURL,
                           data.usernameField,
                           data.newPasswordField,
                           data.oldPasswordField,
                           msg.objects.openerTopWindow,
                           msg.target);
+
+        const flow_id = msg.target.ownerGlobal.gBrowser.getTabForBrowser(msg.target).linkedPanel;
+        Services.telemetry.recordEvent("savant", "login_form", "submit", null,
+                                      {
+                                        subcategory: "encounter",
+                                        flow_id,
+                                      });
         break;
       }
 
       case "RemoteLogins:insecureLoginFormPresent": {
         this.setHasInsecureLoginForms(msg.target, data.hasInsecureLoginForms);
         break;
       }
 
@@ -117,16 +124,28 @@ var LoginManagerParent = {
         const flow_id = msg.target.ownerGlobal.gBrowser.getTabForBrowser(msg.target).linkedPanel;
         Services.telemetry.recordEvent("savant", "pwmgr_use", "use", null,
                                       {
                                         subcategory: "feature",
                                         flow_id,
                                       });
         break;
       }
+
+      case "LoginStats:LoginEncountered": {
+        const canRecordSubmit = (!data.isPrivateWindow && data.isPwmgrEnabled).toString();
+        const flow_id = msg.target.ownerGlobal.gBrowser.getTabForBrowser(msg.target).linkedPanel;
+        Services.telemetry.recordEvent("savant", "login_form", "load", null,
+                                      {
+                                        subcategory: "encounter",
+                                        flow_id,
+                                        canRecordSubmit,
+                                      });
+        break;
+      }
     }
 
     return undefined;
   },
 
   /**
    * Trigger a login form fill and send relevant data (e.g. logins and recipes)
    * to the child process (LoginManagerContent).

--- a/toolkit/components/telemetry/Events.yaml
+++ b/toolkit/components/telemetry/Events.yaml
@@ -250,16 +250,32 @@ savant:
     bug_numbers: [1457226, 1465685]
     notification_emails:
       - "bdanforth@mozilla.com"
       - "shong@mozilla.com"
     expiry_version: "65"
     extra_keys:
       subcategory: The broad event category for this probe. E.g. navigation
       flow_id: A tab identifier to associate events occuring in the same tab
+  login_form:
+    objects: ["load", "submit"]
+    release_channel_collection: opt-out
+    record_in_processes: ["main"]
+    description: >
+      A login form has been loaded or submitted. Login form submit events only
+      fire in non-private windows with Password Manager enabled.
+    bug_numbers: [1457226, 1465685]
+    notification_emails:
+      - "bdanforth@mozilla.com"
+      - "shong@mozilla.com"
+    expiry_version: "65"
+    extra_keys:
+      subcategory: The broad event category for this probe. E.g. navigation
+      flow_id: A tab identifier to associate events occuring in the same tab
+      canRecordSubmit: True if a login form loads in a non-private window with Password Manager enabled.
 
 # This category contains event entries used for Telemetry tests.
 # They will not be sent out with any pings.
 telemetry.test:
   test:
     methods: ["test1", "test2"]
     objects: ["object1", "object2"]
     bug_numbers: [1286606]