diff --git a/src/main/java/mops/gruppen2/controller/Gruppen2Controller.java b/src/main/java/mops/gruppen2/controller/Gruppen2Controller.java
index bff25aa..50be0f2 100644
--- a/src/main/java/mops/gruppen2/controller/Gruppen2Controller.java
+++ b/src/main/java/mops/gruppen2/controller/Gruppen2Controller.java
@@ -7,6 +7,7 @@ import mops.gruppen2.domain.Group;
 import mops.gruppen2.domain.Role;
 import mops.gruppen2.domain.User;
 import mops.gruppen2.domain.event.CreateGroupEvent;
+import mops.gruppen2.domain.event.UpdateRoleEvent;
 import mops.gruppen2.security.Account;
 import mops.gruppen2.service.*;
 import org.keycloak.adapters.springsecurity.token.KeycloakAuthenticationToken;
@@ -88,12 +89,12 @@ public class Gruppen2Controller {
     public String pCreateGroup(KeycloakAuthenticationToken token,
                                @RequestParam(value = "title") String title,
                                @RequestParam(value = "beschreibung") String beschreibung,
-                               @RequestParam(value = "visibility", required = false) Boolean visibility) {
+                               @RequestParam(value = "visibility", required = false) Boolean visibility) throws EventException {
 
         Account account = keyCloakService.createAccountFromPrincipal(token);
         if (visibility == null) {
             visibility = true;
-        }else{
+        } else {
             visibility = false;
         }
         controllerService.createGroup(account, title, beschreibung, visibility);
@@ -132,7 +133,8 @@ public class Gruppen2Controller {
     @PostMapping("/leaveGroup")
     public String pLeaveGroup(KeycloakAuthenticationToken token, @RequestParam (value="group_id") Long id) {
         Account account = keyCloakService.createAccountFromPrincipal(token);
-        controllerService.deleteUser(account, id);
+        User user = new User(account.getName(), account.getGivenname(), account.getFamilyname(), account.getEmail());
+        controllerService.deleteUser(user, id);
         return "redirect:/gruppen2/";
     }
 
@@ -150,4 +152,12 @@ public class Gruppen2Controller {
         }
     }
 
+    @RolesAllowed({"ROLE_orga", "ROLE_studentin", "ROLE_actuator)"})
+    @PostMapping("/changeRole")
+    public String changeRole(KeycloakAuthenticationToken token, @RequestParam (value = "group_id") Long id, 
+                             @RequestParam (value = "user") User user) throws EventException {
+        controllerService.updateRole(user, id);
+        return "redirect:/details/members/";
+    }
+
 }
diff --git a/src/main/java/mops/gruppen2/service/ControllerService.java b/src/main/java/mops/gruppen2/service/ControllerService.java
index 126d519..ff42a16 100644
--- a/src/main/java/mops/gruppen2/service/ControllerService.java
+++ b/src/main/java/mops/gruppen2/service/ControllerService.java
@@ -1,21 +1,20 @@
 package mops.gruppen2.service;
 
-import mops.gruppen2.domain.Group;
-import mops.gruppen2.domain.GroupType;
-import mops.gruppen2.domain.Role;
-import mops.gruppen2.domain.Visibility;
+import mops.gruppen2.domain.*;
+import mops.gruppen2.domain.Exceptions.EventException;
 import mops.gruppen2.domain.event.*;
 import mops.gruppen2.security.Account;
 import org.springframework.stereotype.Service;
-import java.util.*;
 
 @Service
 public class ControllerService {
 
     private final EventService eventService;
+    private final UserService userService;
 
-    public ControllerService(EventService eventService) {
+    public ControllerService(EventService eventService, UserService userService) {
         this.eventService = eventService;
+        this.userService = userService;
     }
 
     /**
@@ -27,23 +26,24 @@ public class ControllerService {
      * @param title Gruppentitel
      * @param description Gruppenbeschreibung
      */
-    public void createGroup(Account account, String title, String description, Boolean visibility) {
+    public void createGroup(Account account, String title, String description, Boolean visibility) throws EventException {
         Visibility visibility1;
         Long group_id = eventService.checkGroup();
 
-        if (visibility){
+        if(visibility) {
             visibility1 = Visibility.PUBLIC;
-        }else{
+        } else {
             visibility1 = Visibility.PRIVATE;
         }
 
         CreateGroupEvent createGroupEvent = new CreateGroupEvent(group_id, account.getName(), null , GroupType.LECTURE, visibility1);
         eventService.saveEvent(createGroupEvent);
+        User user = new User(account.getName(), account.getGivenname(), account.getFamilyname(), account.getEmail());
 
         addUser(account, group_id);
         updateTitle(account, group_id, title);
         updateDescription(account, group_id, description);
-        updateRole(account, group_id);
+        updateRole(user, group_id);
     }
 
     public void addUser(Account account, Long group_id){
@@ -61,13 +61,24 @@ public class ControllerService {
         eventService.saveEvent(updateGroupDescriptionEvent);
     }
 
-    public void updateRole(Account account,Long group_id){
-        UpdateRoleEvent updateRoleEvent = new UpdateRoleEvent(group_id,account.getName(),Role.ADMIN);
+    public void updateRole(User user, Long group_id) throws EventException {
+        UpdateRoleEvent updateRoleEvent;
+        Group group = userService.getGroupById(group_id);
+        if(group.getRoles().get(user.getUser_id()) == Role.ADMIN) {
+            updateRoleEvent = new UpdateRoleEvent(group_id, user.getUser_id(), Role.MEMBER);
+        } else {
+            updateRoleEvent = new UpdateRoleEvent(group_id, user.getUser_id(), Role.ADMIN);
+        }
         eventService.saveEvent(updateRoleEvent);
     }
 
-    public void deleteUser(Account account, Long group_id){
-        DeleteUserEvent deleteUserEvent = new DeleteUserEvent(group_id,account.getName());
+    public void deleteUser(User user, Long group_id){
+        DeleteUserEvent deleteUserEvent = new DeleteUserEvent(group_id, user.getUser_id());
         eventService.saveEvent(deleteUserEvent);
     }
+    
+    public void deleteGroupEvent(User user, Long group_id) {
+        DeleteGroupEvent deleteGroupEvent = new DeleteGroupEvent(group_id, user.getUser_id());
+        eventService.saveEvent(deleteGroupEvent);
+    }
 }