diff --git a/ietf/meeting/urls.py b/ietf/meeting/urls.py
index e4d58d25d..c9c388c0e 100644
--- a/ietf/meeting/urls.py
+++ b/ietf/meeting/urls.py
@@ -54,7 +54,7 @@ type_ietf_only_patterns = [
     url(r'^agendas/edit$', RedirectView.as_view(pattern_name='ietf.meeting.views.list_schedules', permanent=True)),
     url(r'^agendas/diff/$', views.diff_schedules),
     url(r'^agenda/new/$', views.new_meeting_schedule),
-    url(r'^timeslots/edit$',                     views.edit_timeslots),
+    url(r'^timeslots/edit/?$',                     views.edit_timeslots),
     url(r'^timeslot/new$',                       views.create_timeslot),
     url(r'^timeslot/(?P<slot_id>\d+)/edit$',     views.edit_timeslot),
     url(r'^timeslot/(?P<slot_id>\d+)/edittype$', views.edit_timeslot_type),
diff --git a/ietf/static/ietf/css/ietf.css b/ietf/static/ietf/css/ietf.css
index 1ab9e40b2..448827f12 100644
--- a/ietf/static/ietf/css/ietf.css
+++ b/ietf/static/ietf/css/ietf.css
@@ -1239,6 +1239,9 @@ a.fc-event, .fc-event, .fc-content, .fc-title, .fc-event-container {
 .edit-meeting-schedule .session .session-label {
   flex-grow: 1;
   margin-left: 0.1em;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
 }
 
 .edit-meeting-schedule .session .session-label .bof-tag {
@@ -1333,20 +1336,11 @@ a.fc-event, .fc-event, .fc-content, .fc-title, .fc-event-container {
 
 .edit-meeting-schedule .scheduling-panel .preferences {
   margin: 0.5em 0;
-  display: flex;
-  align-items: flex-start;
 }
 
-.edit-meeting-schedule .scheduling-panel .preferences > div {
-  display: flex;
-  flex-direction: column;
-  align-items: flex-start;
-}
-
-.edit-meeting-schedule .scheduling-panel .preferences > div > span {
+.edit-meeting-schedule .scheduling-panel .preferences  > span {
   margin-top: 0;
   margin-right: 1em;
-  white-space: nowrap;
 }
 
 .edit-meeting-schedule .sort-unassigned select {
@@ -1354,17 +1348,20 @@ a.fc-event, .fc-event, .fc-content, .fc-title, .fc-event-container {
   display: inline-block;
 }
 
-.edit-meeting-schedule #timeslot-group-toggles-modal .modal-body {
+.edit-meeting-schedule #timeslot-group-toggles-modal .modal-body > div {
+    margin-bottom: 1.5em;
+}
+.edit-meeting-schedule #timeslot-group-toggles-modal .modal-body .individual-timeslots {
   /*column-count: 3;*/
   display: flex;
   flex-flow: row wrap;
 }
 
-.edit-meeting-schedule #timeslot-group-toggles-modal .modal-body > * {
+.edit-meeting-schedule #timeslot-group-toggles-modal .modal-body .individual-timeslots > * {
   margin-right: 1.5em;
 }
 
-.edit-meeting-schedule #timeslot-group-toggles-modal .modal-body label {
+.edit-meeting-schedule #timeslot-group-toggles-modal .modal-body .individual-timeslots label {
   display: block;
   font-weight: normal;
 }
diff --git a/ietf/static/ietf/js/edit-meeting-schedule.js b/ietf/static/ietf/js/edit-meeting-schedule.js
index add0957b1..191a435ba 100644
--- a/ietf/static/ietf/js/edit-meeting-schedule.js
+++ b/ietf/static/ietf/js/edit-meeting-schedule.js
@@ -738,13 +738,13 @@ jQuery(document).ready(function () {
         timeslots.not(checked.join(",")).addClass('hidden-timeslot-type');
     }
     if (timeSlotTypeInputs.length > 0) {
-        timeSlotTypeInputs.on("click", updateTimeSlotTypeToggling);
+        timeSlotTypeInputs.on("change", updateTimeSlotTypeToggling);
         updateTimeSlotTypeToggling();
     }
 
     // Toggling session purposes
     let sessionPurposeInputs = content.find('.session-purpose-toggles input');
-    function updateSessionPurposeToggling() {
+    function updateSessionPurposeToggling(evt) {
         let checked = [];
         sessionPurposeInputs.filter(":checked").each(function () {
             checked.push(".purpose-" + this.value);
@@ -754,12 +754,24 @@ jQuery(document).ready(function () {
         sessions.not(checked.join(",")).addClass('hidden-purpose');
     }
     if (sessionPurposeInputs.length > 0) {
-        sessionPurposeInputs.on("click", updateSessionPurposeToggling);
+        sessionPurposeInputs.on("change", updateSessionPurposeToggling);
         updateSessionPurposeToggling();
+        content.find('#session-toggles-modal .select-all').get(0).addEventListener(
+          'click',
+          function() {
+              sessionPurposeInputs.prop('checked', true);
+              updateSessionPurposeToggling();
+          });
+        content.find('#session-toggles-modal .clear-all').get(0).addEventListener(
+          'click',
+          function() {
+              sessionPurposeInputs.prop('checked', false);
+              updateSessionPurposeToggling();
+          });
     }
 
     // toggling visible timeslots
-    let timeslotGroupInputs = content.find("#timeslot-group-toggles-modal .modal-body input");
+    let timeslotGroupInputs = content.find("#timeslot-group-toggles-modal .modal-body .individual-timeslots input");
     function updateTimeslotGroupToggling() {
         let checked = [];
         timeslotGroupInputs.filter(":checked").each(function () {
diff --git a/ietf/static/ietf/js/meeting/create_timeslot.js b/ietf/static/ietf/js/meeting/create_timeslot.js
new file mode 100644
index 000000000..7d0cbd271
--- /dev/null
+++ b/ietf/static/ietf/js/meeting/create_timeslot.js
@@ -0,0 +1,43 @@
+// Copyright The IETF Trust 2021, All Rights Reserved
+/* global URLSearchParams */
+(function() {
+  'use strict';
+
+  function initialize() {
+    const form = document.getElementById('timeslot-form');
+    if (!form) {
+      return;
+    }
+
+    const params = new URLSearchParams(document.location.search);
+    const day = params.get('day');
+    const date = params.get('date');
+    const location = params.get('location');
+    const time = params.get('time');
+    const duration = params.get('duration');
+
+    if (day) {
+      const inp = form.querySelector('#id_days input[value="' + day +'"]');
+      if (inp) {
+        inp.checked = true;
+      } else if (date) {
+        const date_field = form.querySelector('#id_other_date');
+        date_field.value = date;
+      }
+    }
+    if (location) {
+      const inp = form.querySelector('#id_locations input[value="' + location + '"]');
+      inp.checked=true;
+    }
+    if (time) {
+      const inp = form.querySelector('input#id_time');
+      inp.value = time;
+    }
+    if (duration) {
+      const inp = form.querySelector('input#id_duration');
+      inp.value = duration;
+    }
+  }
+
+  window.addEventListener('load', initialize);
+})();
\ No newline at end of file
diff --git a/ietf/templates/meeting/create_timeslot.html b/ietf/templates/meeting/create_timeslot.html
index c3ff73058..75a7af0a8 100755
--- a/ietf/templates/meeting/create_timeslot.html
+++ b/ietf/templates/meeting/create_timeslot.html
@@ -1,6 +1,6 @@
 {% extends "base.html" %}
 {# Copyright The IETF Trust 2021, All Rights Reserved #}
-{% load origin %}
+{% load origin static %}
 {% load bootstrap3 %}
 
 {% block pagehead %}
@@ -12,7 +12,7 @@
 {% block content %}
   {% origin %}
   <h1>Create timeslot for {{meeting}}</h1>
-  <form method="post">
+  <form id="timeslot-form" method="post">
     {% csrf_token %}
     {% bootstrap_form form %}
     {% buttons %}
@@ -23,5 +23,6 @@
 {% endblock %}
 
 {% block js %}
+  <script src="{% static 'ietf/js/meeting/create_timeslot.js' %}"></script>
   {{ form.media.js }}
 {% endblock %}
\ No newline at end of file
diff --git a/ietf/templates/meeting/edit_meeting_schedule.html b/ietf/templates/meeting/edit_meeting_schedule.html
index 3bea2dba5..6f6fd6c0b 100644
--- a/ietf/templates/meeting/edit_meeting_schedule.html
+++ b/ietf/templates/meeting/edit_meeting_schedule.html
@@ -175,48 +175,27 @@
         </div>
 
         <div class="preferences">
-          <div>
-            <span class="sort-unassigned">
-              Sort unassigned:
-              <select name="sort_unassigned" class="form-control">
-                <option value="name" selected="selected">By name</option>
-                <option value="parent">By area</option>
-                <option value="duration">By duration</option>
-                <option value="comments">Special requests</option>
-              </select>
-            </span>
+          <span class="sort-unassigned">
+            Sort unassigned:
+            <select name="sort_unassigned" class="form-control">
+              <option value="name" selected="selected">By name</option>
+              <option value="parent">By area</option>
+              <option value="duration">By duration</option>
+              <option value="comments">Special requests</option>
+            </select>
+          </span>
 
-            <span class="timeslot-group-toggles">
-              <button class="btn btn-default" data-toggle="modal" data-target="#timeslot-group-toggles-modal"><input type="checkbox" checked="checked" disabled> Timeslots</button>
-            </span>
-          </div>
+          <span class="toggle-inputs session-parent-toggles">
+            Show:
+            {% for p in session_parents %}
+              <label class="parent-{{ p.acronym }}"><input type="checkbox" checked value="{{ p.acronym }}"> {{ p.acronym }}</label>
+            {% endfor %}
+          </span>
 
-          <div>
-            <span class="toggle-inputs session-parent-toggles">
-              Show:
-              {% for p in session_parents %}
-                <label class="parent-{{ p.acronym }}"><input type="checkbox" checked value="{{ p.acronym }}"> {{ p.acronym }}</label>
-              {% endfor %}
-            </span>
-
-            {% if session_purposes|length > 1 %}
-              <span class="toggle-inputs session-purpose-toggles">
-                Purpose:
-                {% for purpose in session_purposes %}
-                  <label class="purpose-{{ purpose.slug }}"><input type="checkbox" checked value="{{ purpose.slug }}"> {{ purpose }}</label>
-                {% endfor %}
-              </span>
-            {% endif %}
-
-            {% if timeslot_types|length > 1 %}
-              <span class="toggle-inputs timeslot-type-toggles">
-                Type:
-                {% for type in timeslot_types %}
-                  <label class="timeslot-type-{{ type.slug }}"><input type="checkbox" checked value="{{ type.slug }}"> {{ type }}</label>
-                {% endfor %}
-              </span>
-            {% endif %}
-          </div>
+          {% if session_purposes|length > 1 %}
+            <button class="btn btn-default" data-toggle="modal" data-target="#session-toggles-modal"><input type="checkbox" checked="checked" disabled> Sessions</button>
+          {% endif %}
+          <button class="btn btn-default" data-toggle="modal" data-target="#timeslot-group-toggles-modal"><input type="checkbox" checked="checked" disabled> Timeslots</button>
         </div>
       </div>
 
@@ -235,14 +214,52 @@
           </div>
 
           <div class="modal-body">
-            {% for day, t_groups in timeslot_groups %}
-              <div>
-                <div><strong>{{ day|date:"M. d" }}</strong></div>
-                {% for start, end, key in t_groups %}
-                  <label><input type="checkbox" name="timeslot-group" value="{{ key }}" checked="checked"> {{ start|date:"H:i" }} - {{ end|date:"H:i" }}</label>
+            <div class="individual-timeslots">
+              {% for day, t_groups in timeslot_groups %}
+                <div>
+                  <div><strong>{{ day|date:"M. d" }}</strong></div>
+                  {% for start, end, key in t_groups %}
+                    <label><input type="checkbox" name="timeslot-group" value="{{ key }}" checked="checked"> {{ start|date:"H:i" }} - {{ end|date:"H:i" }}</label>
+                  {% endfor %}
+                </div>
+              {% endfor %}
+            </div>
+            <div class="timeslots-by-type timeslot-type-toggles">
+                Type:
+                {% for type in timeslot_types %}
+                  <label class="timeslot-type-{{ type.slug }}"><input type="checkbox" checked value="{{ type.slug }}"> {{ type }}</label>
                 {% endfor %}
-              </div>
-            {% endfor %}
+            </div>
+          </div>
+
+          <div class="modal-footer">
+            <button type="button" class="btn btn-primary" data-dismiss="modal">Close</button>
+          </div>
+        </div>
+      </div>
+    </div>
+
+    <div id="session-toggles-modal" class="modal" role="dialog" aria-labelledby="session-toggles-modal-title">
+      <div class="modal-dialog modal-lg" role="document">
+        <div class="modal-content">
+          <div class="modal-header">
+            <button type="button" class="close" data-dismiss="modal">
+              <span aria-hidden="true">&times;</span>
+              <span class="sr-only">Close</span>
+            </button>
+            <h4 class="modal-title" id="session-toggles-modal-title">Displayed sessions</h4>
+          </div>
+
+          <div class="modal-body">
+            <div class="session-purpose-toggles">
+              {% for purpose in session_purposes %}
+                <div>
+                  <label class="purpose-{{ purpose.slug }}"><input type="checkbox" checked value="{{ purpose.slug }}"> {{ purpose }}</label>
+                </div>
+              {% endfor %}
+              <button type="button" class="btn btn-default select-all">Select all</button>
+              <button type="button" class="btn btn-default clear-all">Clear all</button>
+            </div>
           </div>
 
           <div class="modal-footer">
diff --git a/ietf/templates/meeting/timeslot_edit.html b/ietf/templates/meeting/timeslot_edit.html
index dbdfb02a1..03d296e29 100644
--- a/ietf/templates/meeting/timeslot_edit.html
+++ b/ietf/templates/meeting/timeslot_edit.html
@@ -1,15 +1,33 @@
 {% extends "base.html" %}
 {# Copyright The IETF Trust 2015, All Rights Reserved #}
 {% load origin %}
-{% load agenda_custom_tags %}
+{% load agenda_custom_tags misc_filters %}
 
 {% block title %}IETF {{ meeting.number }} Meeting Agenda: Timeslots and Room Availability{% endblock %}
 
 {% block morecss %}
-  .tstable { width: 100%;}
+  {% comment %}
+  Put scrollbars on the editor table. Requires fixed height so the scroll bars appear on the div, not the page body.
+  Note that 100vh is viewport height. Using that minus 25rem seems to leave space for the page header/footer.
+  {% endcomment %}
+  .timeslot-edit { overflow: auto; height: max(30rem, calc(100vh - 25rem));}
+  .tstable { width: 100%; border-collapse: separate; } {# "separate" to ensure sticky cells keep their borders #}
+  .tstable thead  { position: sticky; top: 0; z-index: 2; background-color: white;}
+  .tstable th:first-child, .tstable td:first-child {
+    background-color: white; {# needs to match the lighter of the striped-table colors! #}
+    position: sticky;
+    left: 0;
+    z-index: 1.5; {# render above other cells / borders but below thead (z-index 2, above) #}
+  }
+  .tstable tbody > tr:nth-of-type(odd) > th:first-child {
+    background-color: rgb(249, 249, 249); {# needs to match the darker of the striped-table colors! #}
+  }
+
   .tstable th { white-space: nowrap;}
   .tstable td { white-space: nowrap;}
   .capacity { font-size:80%; font-weight: normal;}
+
+  a.new-timeslot-link { color: lightgray; font-size: large;}
 {% endblock %}
 
 {% block content %}
@@ -90,15 +108,21 @@
               <a href="{% url "ietf.meeting.views.create_timeslot" num=meeting.number %}">Create a timeslot.</a>
             </td>
           {% else %}
-            {% for day in time_slices %}
-              {% for slice in date_slices|lookup:day %}{% with cell_ts=ts_list.popleft %}
+            {% for day in time_slices %}{% with slots=slot_slices|lookup:day %}
+              {% for slice in date_slices|lookup:day %}{% with cell_ts=ts_list.popleft slot=slots|index:forloop.counter0 %}
                 <td class="tscell {% if cell_ts|length > 1 %}timeslot-collision {% endif %}{% for ts in cell_ts %}tstype_{{ ts.type.slug }} {% endfor %}">
-                {% for ts in cell_ts %}
-                  {% include 'meeting/timeslot_edit_timeslot.html' with ts=ts in_use=ts_with_any_assignments in_official_use=ts_with_official_assignments only %}
-                {% endfor %}
+                {% if cell_ts %}
+                  {% for ts in cell_ts %}
+                    {% include 'meeting/timeslot_edit_timeslot.html' with ts=ts in_use=ts_with_any_assignments in_official_use=ts_with_official_assignments only %}
+                  {% endfor %}
+                {% endif %}
+                <a class="new-timeslot-link {% if cell_ts %}hidden{% endif %}"
+                   href="{% url "ietf.meeting.views.create_timeslot" num=meeting.number %}?day={{ day.toordinal }}&date={{ day|date:"Y-m-d" }}&location={{ room.pk }}&time={{ slot.time|date:'H:i' }}&duration={{ slot.duration }}">
+                  <span class="fa fa-plus-square"></span>
+                </a>
               {% endwith %}{% endfor %}
               </td>
-            {% endfor %}
+            {% endwith %}{% endfor %}
           {% endif %}
         </tr>
       {% endfor %}
@@ -378,7 +402,12 @@
       .error(function(jqXHR, textStatus) {
         displayError('Error deleting timeslot: ' + jqXHR.responseText)
       })
-      .done(function () {timeslotElts.forEach(tse => tse.parentNode.removeChild(tse))})
+      .done(function () {timeslotElts.forEach(
+        tse => {
+          tse.closest('td.tscell').querySelector('.new-timeslot-link').classList.remove('hidden');
+          tse.parentNode.removeChild(tse);
+        }
+      )})
       .always(function () {deleteModal.modal('hide')});
     }
 
diff --git a/ietf/utils/templatetags/misc_filters.py b/ietf/utils/templatetags/misc_filters.py
index a6cbd3cbc..4bf73c2e5 100644
--- a/ietf/utils/templatetags/misc_filters.py
+++ b/ietf/utils/templatetags/misc_filters.py
@@ -60,3 +60,13 @@ def keep_only(items, arg):
       present and truthy. The attribute can be an int or a string.
     """
     return [item for item, value in zip(items, list_extract(items, arg)) if value]
+
+@register.filter
+def index(container, index):
+    """Retrieve item from an indexable container
+
+    Usage: {{ item_list|index:forloop.counter0 }}
+      Returns the index corresponding to the loop counter. (For a literal value,
+      just use the {{ item_list.0 }} syntax.)
+    """
+    return container[index]