diff --git a/devtools/client/responsive.html/index.js b/devtools/client/responsive.html/index.js
index c6eb95b86357..f45b135921c1 100644
--- a/devtools/client/responsive.html/index.js
+++ b/devtools/client/responsive.html/index.js
@@ -40,7 +40,7 @@ const bootstrap = {
     // toolbox session id.
     this.telemetry.toolOpened("responsive", -1, this);
 
-    const store = this.store = Store();
+    const store = this.store = Store({ telemetry: this.telemetry });
     const provider = createElement(Provider, { store }, App());
     ReactDOM.render(provider, document.querySelector("#root"));
     message.post(window, "init:done");
diff --git a/devtools/client/responsive.html/middleware/moz.build b/devtools/client/responsive.html/middleware/moz.build
new file mode 100644
index 000000000000..1f275d5552e1
--- /dev/null
+++ b/devtools/client/responsive.html/middleware/moz.build
@@ -0,0 +1,8 @@
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    'telemetry.js',
+)
diff --git a/devtools/client/responsive.html/middleware/telemetry.js b/devtools/client/responsive.html/middleware/telemetry.js
new file mode 100644
index 000000000000..c92dba9dfaf5
--- /dev/null
+++ b/devtools/client/responsive.html/middleware/telemetry.js
@@ -0,0 +1,69 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const { debounce } = require("devtools/shared/debounce");
+const {
+  RESIZE_VIEWPORT,
+  ROTATE_VIEWPORT,
+} = require("../actions/index");
+const TELEMETRY_SCALAR_VIEWPORT_CHANGE_COUNT =
+  "devtools.responsive.viewport_change_count";
+
+/**
+ * Redux middleware to observe actions dispatched to the Redux store and log to Telemetry.
+ *
+ * `telemetryMiddleware()` is a wrapper function which receives the Telemetry
+ * instance as its only argument and is used to create a closure to make that instance
+ * available to the returned Redux middleware and functions nested within.
+ *
+ * To be used with `applyMiddleware()` helper when creating the Redux store.
+ * @see https://redux.js.org/api/applymiddleware
+ *
+ * The wrapper returns the function that acts as the Redux middleware. This function
+ * receives a single `store` argument (the Redux Middleware API, an object containing
+ * `getState()` and `dispatch()`) and returns a function which receives a single `next`
+ * argument (the next middleware in the chain) which itself returns a function that
+ * receives a single `action` argument (the dispatched action).
+ *
+ * @param  {Object} telemetry
+ *         Instance of the Telemetry API
+ * @return {Function}
+ */
+function telemetryMiddleware(telemetry) {
+  function logViewportChange() {
+    telemetry.scalarAdd(TELEMETRY_SCALAR_VIEWPORT_CHANGE_COUNT, 1);
+  }
+
+  // Debounced logging to use in response to high frequency actions like RESIZE_VIEWPORT.
+  // Set debounce()'s `immediate` parameter to `true` to ensure the very first
+  // call is executed immediately. This helps the tests to check that logging is working
+  // without adding needless complexity to wait for the debounced call.
+  const logViewportChangeDebounced = debounce(logViewportChange, 300, null, true);
+
+  // This cascade of functions is the Redux middleware signature.
+  // @see https://redux.js.org/api/applymiddleware#arguments
+  return store => next => action => {
+    const res = next(action);
+    // Pass through to the next middleware if a telemetry instance is not available, for
+    // example when running unit tests.
+    if (!telemetry) {
+      return res;
+    }
+
+    switch (action.type) {
+      case ROTATE_VIEWPORT:
+        logViewportChange();
+        break;
+      case RESIZE_VIEWPORT:
+        logViewportChangeDebounced();
+        break;
+    }
+
+    return res;
+  };
+}
+
+module.exports = telemetryMiddleware;
diff --git a/devtools/client/responsive.html/moz.build b/devtools/client/responsive.html/moz.build
index 076277dd96f2..dd150a3b8349 100644
--- a/devtools/client/responsive.html/moz.build
+++ b/devtools/client/responsive.html/moz.build
@@ -9,6 +9,7 @@ DIRS += [
     'browser',
     'components',
     'images',
+    'middleware',
     'reducers',
     'utils',
 ]
diff --git a/devtools/client/responsive.html/store.js b/devtools/client/responsive.html/store.js
index 564b1ebe65c7..d9a6037756a6 100644
--- a/devtools/client/responsive.html/store.js
+++ b/devtools/client/responsive.html/store.js
@@ -8,10 +8,12 @@ const { combineReducers } = require("devtools/client/shared/vendor/redux");
 const createStore = require("devtools/client/shared/redux/create-store");
 const reducers = require("./reducers");
 const flags = require("devtools/shared/flags");
+const telemetryMiddleware = require("./middleware/telemetry");
 
-module.exports = function() {
+module.exports = function(options = {}) {
   let shouldLog = false;
   let history;
+  const { telemetry } = options;
 
   // If testing, store the action history in an array
   // we'll later attach to the store
@@ -23,6 +25,7 @@ module.exports = function() {
   const store = createStore({
     log: shouldLog,
     history,
+    middleware: [telemetryMiddleware(telemetry)],
   })(combineReducers(reducers), {});
 
   if (history) {
diff --git a/devtools/client/responsive.html/test/browser/browser.ini b/devtools/client/responsive.html/test/browser/browser.ini
index 7c3d238c2a42..d753a2302505 100644
--- a/devtools/client/responsive.html/test/browser/browser.ini
+++ b/devtools/client/responsive.html/test/browser/browser.ini
@@ -64,6 +64,8 @@ skip-if = true # Bug 1413765
 [browser_tab_remoteness_change.js]
 [browser_target_blank.js]
 [browser_telemetry_activate_rdm.js]
+[browser_telemetry_viewport_change.js]
+skip-if = (os == "mac" && debug)
 [browser_toggle_zoom.js]
 [browser_toolbox_computed_view.js]
 [browser_toolbox_rule_view.js]
diff --git a/devtools/client/responsive.html/test/browser/browser_telemetry_viewport_change.js b/devtools/client/responsive.html/test/browser/browser_telemetry_viewport_change.js
new file mode 100644
index 000000000000..c3836a16325d
--- /dev/null
+++ b/devtools/client/responsive.html/test/browser/browser_telemetry_viewport_change.js
@@ -0,0 +1,29 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Test that actions to change the RDM viewport size and rotation are logged to telemetry.
+ */
+
+const TEST_URL = "data:text/html;charset=utf-8,browser_telemetry_viewport_change.js";
+const TELEMETRY_SCALAR_VIEWPORT_CHANGE_COUNT =
+  "devtools.responsive.viewport_change_count";
+
+addRDMTask(TEST_URL, async function({ ui, manager }) {
+  info("Clear any existing Telemetry scalars");
+  Services.telemetry.clearScalars();
+
+  info("Resize the viewport");
+  await setViewportSize(ui, manager, 100, 300);
+
+  info("Rotate the viewport");
+  rotateViewport(ui);
+
+  const scalars = Services.telemetry.getSnapshotForScalars("main", false);
+  ok(scalars.parent, "Telemetry scalars present");
+
+  const count = scalars.parent[TELEMETRY_SCALAR_VIEWPORT_CHANGE_COUNT];
+  is(count, 2, "Scalar has correct number of viewport changes logged");
+});
diff --git a/devtools/shared/debounce.js b/devtools/shared/debounce.js
index 60636b62e5ef..639949109e80 100644
--- a/devtools/shared/debounce.js
+++ b/devtools/shared/debounce.js
@@ -14,9 +14,12 @@
  *         The wait period
  * @param {Object} scope
  *         The scope to use for func
+ * @param {Boolean} immediate
+ *         Whether to execute the method immediately on the first call.
+ *         Optional. Default `false`.
  * @return {Function} The debounced function
  */
-exports.debounce = function(func, wait, scope) {
+exports.debounce = function(func, wait, scope, immediate = false) {
   let timer = null;
 
   return function() {
@@ -29,5 +32,10 @@ exports.debounce = function(func, wait, scope) {
       timer = null;
       func.apply(scope, args);
     }, wait);
+
+    if (immediate) {
+      immediate = false;
+      func.apply(scope, args);
+    }
   };
 };
diff --git a/toolkit/components/telemetry/Scalars.yaml b/toolkit/components/telemetry/Scalars.yaml
index 41063d28f3a3..5cba39180227 100644
--- a/toolkit/components/telemetry/Scalars.yaml
+++ b/toolkit/components/telemetry/Scalars.yaml
@@ -1570,7 +1570,7 @@ devtools.responsive:
     kind: uint
     notification_emails:
       - dev-developer-tools@lists.mozilla.org
-      - jryans@mozilla.com
+      - mbalfanz@mozilla.com
     record_in_processes:
       - main
     release_channel_collection: opt-out
@@ -1584,7 +1584,20 @@ devtools.responsive:
     keyed: true
     notification_emails:
       - dev-developer-tools@lists.mozilla.org
-      - jryans@mozilla.com
+      - mbalfanz@mozilla.com
+    record_in_processes:
+      - main
+    release_channel_collection: opt-out
+  viewport_change_count:
+    bug_numbers:
+      - 1552464
+    description: >
+      Number of times the viewport attributes changed while in Responsive Design Mode.
+    expires: never
+    kind: uint
+    notification_emails:
+      - dev-developer-tools@lists.mozilla.org
+      - mbalfanz@mozilla.com
     record_in_processes:
       - main
     release_channel_collection: opt-out