diff --git a/dav_events/templates/dav_events/event_detail.html b/dav_events/templates/dav_events/event_detail.html
index c149cf6..2cc8a67 100644
--- a/dav_events/templates/dav_events/event_detail.html
+++ b/dav_events/templates/dav_events/event_detail.html
@@ -3,6 +3,28 @@
 
 {% block head-title %}{{ event }} - {{ block.super }}{% endblock head-title %}
 
+{% block modals %}
+<div id="modal-accept-dialog" class="modal fade" tabindex="-1" role="dialog">
+    <div class="modal-dialog" role="document">
+        <div class="modal-content">
+            <div class="modal-header">
+                <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
+                <h4 class="modal-title">{% trans 'Veranstaltung freigeben?' %}</h4>
+            </div>
+            <div class="modal-body">
+                <p class="text-center">
+                    <strong>{{ event }}</strong>
+                </p>
+            </div>
+            <div class="modal-footer">
+                <a class="btn btn-success" href="{% url 'dav_events:event_accept' event.pk %}">{% trans 'Ja, mach schon!' %}</a>
+                <button type="button" class="btn btn-danger" data-dismiss="modal">{% trans 'Abbrechen' %}</button>
+            </div>
+        </div>
+    </div>
+</div>
+{% endblock modals %}
+
 {% block page-container-fluid %}
 <div class="action-tabs">
     <ul class="nav nav-tabs" role="tablist">
@@ -16,7 +38,8 @@
         </li>
         <li class="{% if not has_permission_accept %}disabled{% endif %}">
             <a class="btn {% if has_permission_accept %}btn-success{% else %}disabled{% endif %}"
-               href="{% url 'dav_events:event_accept' event.pk %}">{% trans 'Freigeben' %}</a>
+               data-toggle="modal" data-target="#modal-accept-dialog"
+               ihref="{% url 'dav_events:event_accept' event.pk %}">{% trans 'Freigeben' %}</a>
         </li>
         <li class="{% if not has_permission_update %}disabled{% endif %}">
             <a class="btn {% if has_permission_update %}btn-warning{% else %}disabled{% endif %}"
diff --git a/dav_events/templates/dav_events/event_update_form.html b/dav_events/templates/dav_events/event_update_form.html
index c4a52e6..17ed64b 100644
--- a/dav_events/templates/dav_events/event_update_form.html
+++ b/dav_events/templates/dav_events/event_update_form.html
@@ -28,8 +28,17 @@
 </div>
 <form action="" method="post">
     {% csrf_token %}
+
+    {% if event.accepted %}
+    <div class="alert alert-danger alert-dismissible" role="alert">
+        <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">&times;</span></button>
+        <strong>{% trans 'Achtung!' %}</strong> {% trans 'Diese Veranstaltung wurde bereits freigegeben.' %}
+        {% trans 'Änderungen müssen mit allen Beteiligten abgesprochen werden.' %}
+    </div>
+    {% endif %}
+
     <div class="panel panel-default">
-        <div class="panel-heading"><h3 class="panel-title">{{ event }}</h3></div>
+        <div class="panel-heading"><h4 class="panel-title">{{ event }}</h4></div>
         <div class="panel-body">
             {% bootstrap_form form layout='horizontal' %}
         </div>