diff --git a/file/lib/data/user/UserAction.class.php b/file/lib/data/user/UserAction.class.php
index ad7b847..64857dd 100644
--- a/file/lib/data/user/UserAction.class.php
+++ b/file/lib/data/user/UserAction.class.php
@@ -21,7 +21,13 @@ class UserAction extends \wcf\data\AbstractDatabaseObjectAction {
 	 * Validates invite preparation.
 	 */
 	public function validatePrepareInvite() {
-		// Todo: Proper validation
+		WCF::getSession()->checkPermissions(array('user.chat.canInvite'));
+		
+		if (!WCF::getUser()->chatRoomID) throw new \wcf\system\exception\PermissionDeniedException();
+		
+		$room = \chat\data\room\RoomCache::getInstance()->getRoom(WCF::getUser()->chatRoomID);
+		
+		if (!$room || !$room->canEnter()) throw new \wcf\system\exception\PermissionDeniedException();
 	}
 	
 	/**
@@ -50,14 +56,15 @@ public function prepareInvite() {
 	 * Validates invites.
 	 */
 	public function validateInvite() {
-		if (!isset($this->parameters['recipients'])) throw new \wcf\system\exception\UserInputException("recipients");
+		WCF::getSession()->checkPermissions(array('user.chat.canInvite'));
 		
-		if (WCF::getUser()->chatRoomID) {
-			$this->room = \chat\data\room\RoomCache::getInstance()->getRoom(WCF::getUser()->chatRoomID);
-		}
-		else {
-			throw new \wcf\system\exception\UserInputException("roomID");
-		}
+		if (!WCF::getUser()->chatRoomID) throw new \wcf\system\exception\PermissionDeniedException();
+		
+		$this->room = \chat\data\room\RoomCache::getInstance()->getRoom(WCF::getUser()->chatRoomID);
+		
+		if (!$this->room || !$this->room->canEnter()) throw new \wcf\system\exception\PermissionDeniedException();
+		
+		if (!isset($this->parameters['recipients'])) throw new \wcf\system\exception\UserInputException("recipients");
 	}
 	
 	/**
diff --git a/language/de.xml b/language/de.xml
index b79d5af..27dd04c 100644
--- a/language/de.xml
+++ b/language/de.xml
@@ -60,6 +60,7 @@
 		<item name="wcf.acp.group.option.user.chat.canEnter"><![CDATA[Kann Chat betreten]]></item>
 		<item name="wcf.acp.group.option.user.chat.canWrite"><![CDATA[Kann im Chat schreiben]]></item>
 		<item name="wcf.acp.group.option.user.chat.canTempRoom"><![CDATA[Kann temporäre Räume erstellen]]></item>
+		<item name="wcf.acp.group.option.user.chat.canInvite"><![CDATA[Kann Benutzer zum Chatten einladen]]></item>
 		<item name="wcf.acp.group.option.user.chat.allowedBBCodes"><![CDATA[Erlaubte BBCodes]]></item>
 		<item name="wcf.acp.group.option.user.chat.allowedBBCodes.description"><![CDATA[Die hier ausgewählten BBCodes dürfen von Mitgliedern dieser Benutzergruppe verwendet werden.]]></item>
 		<item name="wcf.acp.group.option.user.chat.canUploadAttachment"><![CDATA[Kann Dateien anhängen]]></item>
diff --git a/language/en.xml b/language/en.xml
index 737cc90..2ed941b 100644
--- a/language/en.xml
+++ b/language/en.xml
@@ -40,8 +40,8 @@
 	</category>
 	
 	<category name="chat.notification">
-		<item name="chat.notification.invited.title"><![CDATA[TODO: Jemand möchte mit Ihnen chatten!]]></item>
-		<item name="chat.notification.invited.message"><![CDATA[TODO: „{$author->username}“ möchte mit Ihnen im Chatraum „{$userNotificationObject->getTitle()}“ chatten!]]></item>
+		<item name="chat.notification.invited.title"><![CDATA[Someone wants to chat with you!]]></item>
+		<item name="chat.notification.invited.message"><![CDATA[“{$author->username}” wants to chat with you in “{$userNotificationObject->getTitle()}”!]]></item>
 	</category>
 	
 	<category name="wcf.acl.option">
@@ -60,6 +60,7 @@
 		<item name="wcf.acp.group.option.user.chat.canEnter"><![CDATA[Can enter chat]]></item>
 		<item name="wcf.acp.group.option.user.chat.canWrite"><![CDATA[Can write messages]]></item>
 		<item name="wcf.acp.group.option.user.chat.canTempRoom"><![CDATA[Can create temporary rooms]]></item>
+		<item name="wcf.acp.group.option.user.chat.canInvite"><![CDATA[Can invite users to chat]]></item>
 		<item name="wcf.acp.group.option.user.chat.allowedBBCodes"><![CDATA[Allowed BBCodes]]></item>
 		<item name="wcf.acp.group.option.user.chat.allowedBBCodes.description"><![CDATA[Selected BBCodes may be used by members of this group.]]></item>
 		<item name="wcf.acp.group.option.user.chat.canUploadAttachment"><![CDATA[Can upload attachments]]></item>
diff --git a/template/chat.tpl b/template/chat.tpl
index 0d8e9c9..f3c59c8 100644
--- a/template/chat.tpl
+++ b/template/chat.tpl
@@ -192,12 +192,14 @@
 							</li>
 						{/if}
 						
-						<li>
-							<a id="timsChatInvite" class="button jsTooltip" title="{lang}chat.global.invite{/lang}">
-								<span class="icon icon16 icon-user"></span>
-								<span class="invisible">{lang}chat.global.invite{/lang}</span>
-							</a>
-						</li>
+						{if $__wcf->session->getPermission('user.chat.canInvite')}
+							<li>
+								<a id="timsChatInvite" class="button jsTooltip" title="{lang}chat.global.invite{/lang}">
+									<span class="icon icon16 icon-user"></span>
+									<span class="invisible">{lang}chat.global.invite{/lang}</span>
+								</a>
+							</li>
+						{/if}
 						
 						<li>
 							<a id="timsChatClear" class="button jsTooltip" title="{lang}chat.global.clear{/lang}">
diff --git a/userGroupOption.xml b/userGroupOption.xml
index 4d41e94..57e4d37 100644
--- a/userGroupOption.xml
+++ b/userGroupOption.xml
@@ -35,6 +35,13 @@
 				<admindefaultvalue>1</admindefaultvalue>
 				<usersonly>1</usersonly>
 			</option>
+			<option name="user.chat.canInvite">
+				<categoryname>user.chat</categoryname>
+				<optiontype>boolean</optiontype>
+				<defaultvalue>0</defaultvalue>
+				<admindefaultvalue>1</admindefaultvalue>
+				<usersonly>1</usersonly>
+			</option>
 			<option name="user.chat.allowedBBCodes">
 				<categoryname>user.chat</categoryname>
 				<optiontype>BBCodeSelect</optiontype>