diff --git a/admin/admin_settings.php b/admin/admin_settings.php
index 7d3f1d22..9f3d82e6 100644
--- a/admin/admin_settings.php
+++ b/admin/admin_settings.php
@@ -552,6 +552,14 @@ if (defined('HESK_DEMO')) {
                 <li class="active"><a href="#general" data-toggle="tab"><?php echo $hesklang['tab_1']; ?></a></li>
                 <li><a href="#helpdesk" data-toggle="tab"><?php echo $hesklang['tab_2']; ?></a></li>
                 <li><a href="#knowledgebase" data-toggle="tab"><?php echo $hesklang['tab_3']; ?></a></li>
+                <li>
+                    <a href="#calendar" data-toggle="tab"><?php echo $hesklang['calendar_title_case']; ?>
+                        <span class="label label-primary" data-toggle="tooltip"
+                              title="<?php echo $hesklang['added_in_mods_for_hesk']; ?>">
+                            <?php echo $hesklang['mods_for_hesk_acronym']; ?>
+                        </span>
+                    </a>
+                </li>
                 <li><a href="#customFields" data-toggle="tab"><?php echo $hesklang['tab_4']; ?></a></li>
                 <li><a href="#email" data-toggle="tab"><?php echo $hesklang['tab_6']; ?></a></li>
                 <li><a href="#ticket-list" data-toggle="tab"><?php echo $hesklang['tab_7']; ?></a></li>
@@ -1970,6 +1978,64 @@ if (defined('HESK_DEMO')) {
                     </div>
                 </div>
 
+                <!-- Calendar Tab -->
+                <div class="tab-pane fade in" id="calendar">
+                    <h6 class="bold"><?php echo $hesklang['calendar_settings']; ?></h6>
+                    <div class="footerWithBorder blankSpace"></div>
+                    <div class="form-group">
+                        <label for="enable-calendar" class="col-sm-4 col-xs-12 control-label">
+                            <?php echo $hesklang['enable_calendar']; ?>
+                            <i class="fa fa-question-circle settingsquestionmark" data-toggle="popover"
+                               title="<?php echo $hesklang['custom_field_setting']; ?>"
+                               data-content="<?php echo $hesklang['custom_field_setting_help']; ?>"></i>
+                        </label>
+                        <div class="col-sm-8 form-inline">
+                            <?php
+                            $on = $modsForHesk_settings['enable_calendar'] == 1 ? 'checked="checked"' : '';
+                            $off = $modsForHesk_settings['enable_calendar'] ? '' : 'checked="checked"';
+                            $only = $modsForHesk_settings['enable_calendar'] == 2 ? 'checked="checked"' : '';
+                            echo '
+                        <div class="radio"><label><input type="radio" name="s_enable_calendar" value="1" ' . $on . ' /> ' . $hesklang['yes_enable_calendar'] . '</label></div><br>
+                        <div class="radio"><label><input type="radio" name="s_enable_calendar" value="2" ' . $only . ' /> ' . $hesklang['yes_enable_calendar_staff_only'] . '</label></div><br>
+                        <div class="radio"><label><input type="radio" name="s_enable_calendar" value="0" ' . $off . ' /> ' . $hesklang['no_disable_calendar'] . '</label></div>';
+                            ?>
+                        </div>
+                    </div>
+                    <div class="form-group">
+                        <label for="first-day-of-week" class="col-sm-4 col-xs-12 control-label">
+                            <?php echo $hesklang['first_day_of_week']; ?>
+                            <i class="fa fa-question-circle settingsquestionmark" data-toggle="popover"
+                               title="<?php echo $hesklang['custom_field_setting']; ?>"
+                               data-content="<?php echo $hesklang['custom_field_setting_help']; ?>"></i>
+                        </label>
+                        <div class="col-sm-8 col-xs-12">
+                            <select name="first-day-of-week" class="form-control">
+                                <option value="0" <?php if ($modsForHesk_settings['first_day_of_week'] == '0') { echo 'selected'; } ?>>
+                                    <?php echo $hesklang['d0']; ?>
+                                </option>
+                                <option value="1" <?php if ($modsForHesk_settings['first_day_of_week'] == '1') { echo 'selected'; } ?>>
+                                    <?php echo $hesklang['d1']; ?>
+                                </option>
+                                <option value="2" <?php if ($modsForHesk_settings['first_day_of_week'] == '2') { echo 'selected'; } ?>>
+                                    <?php echo $hesklang['d2']; ?>
+                                </option>
+                                <option value="3" <?php if ($modsForHesk_settings['first_day_of_week'] == '3') { echo 'selected'; } ?>>
+                                    <?php echo $hesklang['d3']; ?>
+                                </option>
+                                <option value="4" <?php if ($modsForHesk_settings['first_day_of_week'] == '4') { echo 'selected'; } ?>>
+                                    <?php echo $hesklang['d4']; ?>
+                                </option>
+                                <option value="5" <?php if ($modsForHesk_settings['first_day_of_week'] == '5') { echo 'selected'; } ?>>
+                                    <?php echo $hesklang['d5']; ?>
+                                </option>
+                                <option value="6" <?php if ($modsForHesk_settings['first_day_of_week'] == '6') { echo 'selected'; } ?>>
+                                    <?php echo $hesklang['d6']; ?>
+                                </option>
+                            </select>
+                        </div>
+                    </div>
+                </div>
+
                 <!-- Custom Fields Tab -->
                 <div class="tab-pane fade in" id="customFields">
                     <h6 class="bold"><?php echo $hesklang['custom_use']; ?> <a href="Javascript:void(0)"
diff --git a/admin/calendar.php b/admin/calendar.php
index 6e34289c..0f87fe7d 100644
--- a/admin/calendar.php
+++ b/admin/calendar.php
@@ -43,9 +43,6 @@ hesk_session_start();
 hesk_dbConnect();
 hesk_isLoggedIn();
 
-/* Check permissions for this feature */
-//hesk_checkPermission('can_service_msg');
-
 // Define required constants
 if (hesk_checkPermission('can_man_calendar', 0)) {
     define('MFH_CALENDAR', 1);
@@ -53,6 +50,12 @@ if (hesk_checkPermission('can_man_calendar', 0)) {
     define('MFH_CALENDAR_READONLY', 1);
 }
 
+// Is the calendar enabled?
+$modsForHesk_settings = mfh_getSettings();
+if ($modsForHesk_settings['enable_calendar'] == '0') {
+    hesk_error($hesklang['calendar_disabled']);
+}
+
 // Get categories for the dropdown
 $rs = hesk_dbQuery("SELECT `id`, `name`, `color` FROM `" . hesk_dbEscape($hesk_settings['db_pfix']) . "categories` WHERE `usage` <> 1 ORDER BY `cat_order`");
 $categories = [];
@@ -490,6 +493,7 @@ require_once(HESK_PATH . 'inc/show_admin_nav.inc.php');
     <p id="lang_error_updating_event"><?php echo $hesklang['error_updating_event']; ?></p>
     <p id="lang_ticket_due_date_updated"><?php echo $hesklang['ticket_due_date_updated']; ?></p>
     <p id="lang_error_updating_ticket_due_date"><?php echo $hesklang['error_updating_ticket_due_date']; ?></p>
+    <p id="setting_first_day_of_week"><?php echo $modsForHesk_settings['first_day_of_week']; ?></p>
 </div>
 <?php
 
diff --git a/calendar.php b/calendar.php
index 5899e24b..141c0a9f 100644
--- a/calendar.php
+++ b/calendar.php
@@ -47,6 +47,11 @@ hesk_session_start();
 hesk_dbConnect();
 $modsForHesk_settings = mfh_getSettings();
 
+// Is the calendar enabled?
+if ($modsForHesk_settings['enable_calendar'] != '1') {
+    hesk_error($hesklang['calendar_disabled']);
+}
+
 $categories = [];
 $orderBy = $modsForHesk_settings['category_order_column'];
 $categorySql = "SELECT * FROM `" . hesk_dbEscape($hesk_settings['db_pfix']) . "categories` WHERE `usage` <> 1 AND `type` = '0' ORDER BY '" . $orderBy . "'";
diff --git a/install/mods-for-hesk/sql/installSql.php b/install/mods-for-hesk/sql/installSql.php
index a07e9ee1..853725aa 100644
--- a/install/mods-for-hesk/sql/installSql.php
+++ b/install/mods-for-hesk/sql/installSql.php
@@ -741,5 +741,7 @@ function execute260Scripts()
     executeQuery("ALTER TABLE `" . hesk_dbEscape($hesk_settings['db_pfix']) . "categories` ADD COLUMN `color` VARCHAR(7)");
     executeQuery("ALTER TABLE `" . hesk_dbEscape($hesk_settings['db_pfix']) . "categories` ADD COLUMN `usage` INT NOT NULL DEFAULT 0");
     executeQuery("ALTER TABLE `" . hesk_dbEscape($hesk_settings['db_pfix']) . "users` ADD COLUMN `notify_overdue_unassigned` ENUM('0', '1') NOT NULL DEFAULT '0' AFTER `notify_note_unassigned`");
+    executeQuery("INSERT INTO `" . hesk_dbEscape($hesk_settings['db_pfix']) . "settings` (`Key`, `Value`) VALUES ('enable_calendar', '1')");
+    executeQuery("INSERT INTO `" . hesk_dbEscape($hesk_settings['db_pfix']) . "settings` (`Key`, `Value`) VALUES ('first_day_of_week', '0')");
     executeQuery("UPDATE `" . hesk_dbEscape($hesk_settings['db_pfix']) . "settings` SET `Value` = '2.6.0' WHERE `Key` = 'modsForHeskVersion'");
 }
\ No newline at end of file
diff --git a/js/calendar/mods-for-hesk-calendar.js b/js/calendar/mods-for-hesk-calendar.js
index b80ebf9c..fcb05806 100644
--- a/js/calendar/mods-for-hesk-calendar.js
+++ b/js/calendar/mods-for-hesk-calendar.js
@@ -9,6 +9,7 @@ $(document).ready(function() {
         eventLimit: true,
         timeFormat: 'H:mm',
         axisFormat: 'H:mm',
+        firstDay: $('#setting_first_day_of_week').text(),
         events: function(start, end, timezone, callback) {
             $.ajax({
                 url: getHelpdeskUrl() + '/internal-api/admin/calendar/?start=' + start + '&end=' + end,
diff --git a/language/en/text.php b/language/en/text.php
index 243894f1..9513633b 100644
--- a/language/en/text.php
+++ b/language/en/text.php
@@ -85,6 +85,13 @@ $hesklang['can_man_calendar'] = 'Can manage calendar events';
 $hesklang['calendar_reminder'] = 'Upcoming Event: %%TITLE%%';
 $hesklang['overdue_ticket'] = '[%%TRACKID%%] Ticket Overdue!';
 $hesklang['notify_overdue_unassigned'] = 'A ticket is overdue not assigned to me';
+$hesklang['calendar_settings'] = 'Calendar Settings';
+$hesklang['enable_calendar'] = 'Enable calendar';
+$hesklang['yes_enable_calendar'] = '<b>YES</b>, enable calendar';
+$hesklang['yes_enable_calendar_staff_only'] = '<b>YES</b>, enable calendar, but only for staff';
+$hesklang['no_disable_calendar'] = '<b>NO</b>, disable calendar';
+$hesklang['first_day_of_week'] = 'First day of week';
+$hesklang['calendar_disabled'] = 'The calendar is disabled';
 
 // ADDED OR MODIFIED IN Mods for HESK 2.5.2
 $hesklang['manage_statuses'] = 'Manage Statuses';