diff --git a/frontend_tests/node_tests/compose.js b/frontend_tests/node_tests/compose.js
index 42048fd74f..be1f729d6d 100644
--- a/frontend_tests/node_tests/compose.js
+++ b/frontend_tests/node_tests/compose.js
@@ -1062,6 +1062,64 @@ function test_with_mock_socket(test_params) {
         preventDefault: noop,
     };
 
+    (function test_stream_name_completed_triggered() {
+        var handler = $(document).get_on_handler('streamname_completed.zulip');
+
+        var data = {
+            stream: {
+                name: 'Denmark',
+            },
+        };
+
+        function test_noop_case(invite_only) {
+            compose_state.set_message_type('stream');
+            data.stream.invite_only = invite_only;
+            handler({}, data);
+            assert.equal($('#compose_private_stream_alert').visible(), false);
+        }
+
+        test_noop_case(false);
+
+        $("#compose_private").hide();
+        compose_state.set_message_type('stream');
+
+        var checks = [
+           (function () {
+               var called;
+               templates.render = function (template_name, context) {
+                   called = true;
+                   assert.equal(template_name, 'compose_private_stream_alert');
+                   assert.equal(context.invite_only, true);
+                   assert.equal(context.stream_name, 'Denmark');
+                   return 'fake-compose_private_stream_alert-template';
+               };
+               return function () { assert(called); };
+           }()),
+
+           (function () {
+              var called;
+              $("#compose_private_stream_alert").append = function (html) {
+                  called = true;
+                  assert.equal(html, 'fake-compose_private_stream_alert-template');
+              };
+              return function () { assert(called); };
+           }()),
+        ];
+
+        data = {
+           stream: {
+               invite_only: true,
+               name: 'Denmark',
+           },
+        };
+
+        handler({}, data);
+        assert.equal($('#compose_private_stream_alert').visible(), true);
+
+        _.each(checks, function (f) { f(); });
+
+    }());
+
     (function test_attach_files_compose_clicked() {
         var handler = $("#compose")
                         .get_on_handler("click", "#attach_files");
diff --git a/frontend_tests/node_tests/templates.js b/frontend_tests/node_tests/templates.js
index c1fc10adb8..d8b286285e 100644
--- a/frontend_tests/node_tests/templates.js
+++ b/frontend_tests/node_tests/templates.js
@@ -518,6 +518,15 @@ function render(template_name, args) {
     assert.equal(a.text(), "Narrow to here");
 }());
 
+(function compose_private_stream_alert() {
+    var args = {
+      name: 'Demark',
+      invite_only: true,
+    };
+    var html = render('compose_private_stream_alert', args);
+    global.write_handlebars_output("compose_stream_alert", html);
+}());
+
 (function dev_env_email_access() {
     var html = render('dev_env_email_access');
     global.write_handlebars_output("dev_env_email_access", html);
diff --git a/static/js/compose.js b/static/js/compose.js
index 13800a64fc..9fb305c45f 100644
--- a/static/js/compose.js
+++ b/static/js/compose.js
@@ -68,6 +68,11 @@ exports.clear_invites = function () {
     $("#compose_invite_users").empty();
 };
 
+exports.clear_private_stream_alert = function () {
+    $("#compose_private_stream_alert").hide();
+    $("#compose_private_stream_alert").empty();
+};
+
 exports.reset_user_acknowledged_all_everyone_flag = function () {
     user_acknowledged_all_everyone = undefined;
 };
@@ -307,6 +312,7 @@ exports.enter_with_preview_open = function () {
 
 exports.finish = function () {
     exports.clear_invites();
+    exports.clear_private_stream_alert();
 
     if (! compose.validate()) {
         return false;
@@ -632,6 +638,39 @@ exports.initialize = function () {
         }
     });
 
+    // Show a warning if a private stream is linked
+    $(document).on('streamname_completed.zulip', function (event, data) {
+        if (compose_state.get_message_type() !== 'stream') {
+            return;
+        }
+
+        if (data !== undefined && data.stream !== undefined) {
+            var invite_only = data.stream.invite_only;
+            var stream_name = data.stream.name;
+
+            if (invite_only) {
+                var warning_area = $("#compose_private_stream_alert");
+                var context = { stream_name: stream_name, invite_only: invite_only };
+                var new_row = templates.render("compose_private_stream_alert", context);
+
+                warning_area.append(new_row);
+                warning_area.show();
+            }
+        }
+
+    });
+
+    $("#compose_private_stream_alert").on('click', '.compose_private_stream_alert_close', function (event) {
+        var stream_alert_row = $(event.target).parents('.compose_private_stream_alert');
+        var stream_alert = $("#compose_private_stream_alert");
+
+        stream_alert_row.remove();
+
+        if (stream_alert.children().length === 0) {
+            stream_alert.hide();
+        }
+    });
+
     // Click event binding for "Attach files" button
     // Triggers a click on a hidden file input field
 
diff --git a/static/js/compose_actions.js b/static/js/compose_actions.js
index df6485af3c..1a1670f680 100644
--- a/static/js/compose_actions.js
+++ b/static/js/compose_actions.js
@@ -92,6 +92,7 @@ function clear_box() {
 
     // TODO: Better encapsulate at-mention warnings.
     compose.clear_all_everyone_warnings();
+    compose.clear_private_stream_alert();
     compose.reset_user_acknowledged_all_everyone_flag();
 
     exports.clear_textarea();
diff --git a/static/styles/compose.css b/static/styles/compose.css
index 558ea23e76..b8d015cf76 100644
--- a/static/styles/compose.css
+++ b/static/styles/compose.css
@@ -192,16 +192,19 @@ table.compose_table {
     top: 5px;
 }
 
-#compose_invite_users {
+#compose_invite_users,
+#compose_private_stream_alert {
     /* Don't overlap into the compose_close × */
     margin-right: 10px;
 }
 
-.compose_invite_user {
+.compose_invite_user,
+.compose_private_stream_alert {
     padding: 4px 0px 4px 0px;
 }
 
-.compose_invite_close {
+.compose_invite_close,
+.compose_private_stream_alert_close {
     display: inline;
     margin-top: 4px;
 
@@ -209,7 +212,8 @@ table.compose_table {
 }
 
 .compose-all-everyone-controls,
-.compose_invite_user_controls {
+.compose_invite_user_controls,
+.compose_private_stream_alert_controls {
     float: right;
     -webkit-transform: translateY(-13%);
     -ms-transform: translateY(-13%);
diff --git a/static/templates/compose_private_stream_alert.handlebars b/static/templates/compose_private_stream_alert.handlebars
new file mode 100644
index 0000000000..bb2c0a8377
--- /dev/null
+++ b/static/templates/compose_private_stream_alert.handlebars
@@ -0,0 +1,6 @@
+<div class="compose_private_stream_alert" data-stream_name="{{stream_name}}">
+    {{#tr this}}Warning: <strong>__stream_name__</strong> is a private stream.{{/tr}}
+    <div class="compose_private_stream_alert_controls">
+        <button type="button" class="compose_private_stream_alert_close close">&times;</button>
+    </div>
+</div>
diff --git a/templates/zerver/compose.html b/templates/zerver/compose.html
index bc55ace00f..c49ffd1546 100644
--- a/templates/zerver/compose.html
+++ b/templates/zerver/compose.html
@@ -36,6 +36,7 @@
       </div>
       <div  id="compose_invite_users" class="alert home-error-bar"></div>
       <div  id="compose-all-everyone" class="alert home-error-bar"></div>
+      <div  id="compose_private_stream_alert" class="alert home-error-bar"></div>
       <div  id="out-of-view-notification" class="notification-alert"></div>
      <div class="composition-area">
       <button type="button" class="close" id='compose_close' title="{{ _('Cancel compose') }} (Esc)">&times;</button>