diff --git a/README.md b/README.md
index 0a29c9a0b..0699ceb77 100755
--- a/README.md
+++ b/README.md
@@ -197,3 +197,7 @@ IDP_CLIENT_SECRET=client-secret
   * 601: The amount of cash that will be added, has to be more than zero
 *EventController 7xx*
   * 701: Event creation parameters are missing
+*EventParticipationController 8xx*
+  * 801: User has no permission to enter or leave
+  * 802: User could not join the event
+  * 803: User could not leave the event
\ No newline at end of file
diff --git a/psalm.baseline.xml b/psalm.baseline.xml
index a3f68a853..1516c5bd5 100755
--- a/psalm.baseline.xml
+++ b/psalm.baseline.xml
@@ -153,8 +153,7 @@
     </UndefinedClass>
   </file>
   <file src="src/Mealz/MealBundle/Service/Doorman.php">
-    <UndefinedInterfaceMethod occurrences="2">
-      <code>getProfile</code>
+    <UndefinedInterfaceMethod occurrences="3">
       <code>getProfile</code>
     </UndefinedInterfaceMethod>
   </file>
diff --git a/src/Mealz/MealBundle/Controller/EventController.php b/src/Mealz/MealBundle/Controller/EventController.php
index 5ff2e32e0..221aa3710 100644
--- a/src/Mealz/MealBundle/Controller/EventController.php
+++ b/src/Mealz/MealBundle/Controller/EventController.php
@@ -4,11 +4,15 @@
 
 namespace App\Mealz\MealBundle\Controller;
 
+use App\Mealz\MealBundle\Entity\Day;
 use App\Mealz\MealBundle\Entity\Event;
+use App\Mealz\MealBundle\Event\EventParticipationUpdateEvent;
 use App\Mealz\MealBundle\Repository\EventRepositoryInterface;
+use App\Mealz\MealBundle\Service\EventParticipationService;
 use Doctrine\ORM\EntityManagerInterface;
 use Exception;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Security;
+use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\Request;
 
@@ -19,13 +23,19 @@ class EventController extends BaseListController
 {
     private EntityManagerInterface $em;
     private EventRepositoryInterface $eventRepo;
+    private EventDispatcherInterface $eventDispatcher;
+    private EventParticipationService $eventPartSrv;
 
     public function __construct(
         EntityManagerInterface $entityManager,
-        EventRepositoryInterface $eventRepository
+        EventRepositoryInterface $eventRepository,
+        EventDispatcherInterface $eventDispatcher,
+        EventParticipationService $eventPartSrv
     ) {
         $this->em = $entityManager;
         $this->eventRepo = $eventRepository;
+        $this->eventDispatcher = $eventDispatcher;
+        $this->eventPartSrv = $eventPartSrv;
     }
 
     public function getEventList(): JsonResponse
@@ -88,4 +98,38 @@ public function delete(Event $event): JsonResponse
             return new JsonResponse(['message' => $e->getMessage(), 500]);
         }
     }
+
+    public function join(Day $day): JsonResponse
+    {
+        $profile = $this->getProfile();
+        if (null === $profile) {
+            return new JsonResponse(['messasge' => '801: User is not allowed to join'], 403);
+        }
+
+        $eventParticipation = $this->eventPartSrv->join($profile, $day);
+        if (null === $eventParticipation) {
+            return new JsonResponse(['messasge' => '802: User could not join the event'], 500);
+        }
+
+        $this->eventDispatcher->dispatch(new EventParticipationUpdateEvent($eventParticipation));
+
+        return new JsonResponse(['isParticipating' => true], 200);
+    }
+
+    public function leave(Day $day): JsonResponse
+    {
+        $profile = $this->getProfile();
+        if (null === $profile) {
+            return new JsonResponse(['messasge' => '801: User is not allowed to leave'], 403);
+        }
+
+        $eventParticipation = $this->eventPartSrv->leave($profile, $day);
+        if (null === $eventParticipation) {
+            return new JsonResponse(['messasge' => '802: User could not leave the event'], 500);
+        }
+
+        $this->eventDispatcher->dispatch(new EventParticipationUpdateEvent($eventParticipation));
+
+        return new JsonResponse(['isParticipating' => false], 200);
+    }
 }
diff --git a/src/Mealz/MealBundle/Entity/EventParticipation.php b/src/Mealz/MealBundle/Entity/EventParticipation.php
index 4926d9aef..977d42e5a 100644
--- a/src/Mealz/MealBundle/Entity/EventParticipation.php
+++ b/src/Mealz/MealBundle/Entity/EventParticipation.php
@@ -96,4 +96,14 @@ public function getParticipants(): ArrayCollection
 
         return new ArrayCollection($this->participants->toArray());
     }
+
+    public function addParticipant(Participant $participant): void
+    {
+        $this->participants->add($participant);
+    }
+
+    public function removeParticipant(Participant $participant): bool
+    {
+        return $this->participants->removeElement($participant);
+    }
 }
diff --git a/src/Mealz/MealBundle/Entity/Participant.php b/src/Mealz/MealBundle/Entity/Participant.php
index 4fee8a2c9..a031d1be0 100644
--- a/src/Mealz/MealBundle/Entity/Participant.php
+++ b/src/Mealz/MealBundle/Entity/Participant.php
@@ -32,9 +32,9 @@ class Participant
      * @Assert\NotNull()
      * @Assert\Type(type="App\Mealz\MealBundle\Entity\Meal")
      * @ORM\ManyToOne(targetEntity="Meal",inversedBy="participants")
-     * @ORM\JoinColumn(name="meal_id", referencedColumnName="id")
+     * @ORM\JoinColumn(name="meal_id", referencedColumnName="id", nullable=true)
      */
-    private Meal $meal;
+    private ?Meal $meal;
 
     /**
      * @Assert\NotNull()
@@ -85,10 +85,11 @@ class Participant
      */
     private bool $confirmed = false;
 
-    public function __construct(Profile $profile, ?Meal $meal)
+    public function __construct(Profile $profile, ?Meal $meal, ?EventParticipation $eventParticipation = null)
     {
         $this->profile = $profile;
         $this->meal = $meal;
+        $this->event = $eventParticipation;
         $this->combinedDishes = new DishCollection();
     }
 
@@ -137,7 +138,7 @@ public function setMeal(Meal $meal): void
         $this->meal = $meal;
     }
 
-    public function getMeal(): Meal
+    public function getMeal(): ?Meal
     {
         return $this->meal;
     }
diff --git a/src/Mealz/MealBundle/Event/MealOfferAcceptedEvent.php b/src/Mealz/MealBundle/Event/MealOfferAcceptedEvent.php
index 214b7fcb7..0db5924d3 100644
--- a/src/Mealz/MealBundle/Event/MealOfferAcceptedEvent.php
+++ b/src/Mealz/MealBundle/Event/MealOfferAcceptedEvent.php
@@ -30,7 +30,7 @@ public function __construct(Participant $participant, Profile $offerer)
         $this->offerer = $offerer;
     }
 
-    public function getMeal(): Meal
+    public function getMeal(): ?Meal
     {
         return $this->participant->getMeal();
     }
diff --git a/src/Mealz/MealBundle/Event/MealOfferCancelledEvent.php b/src/Mealz/MealBundle/Event/MealOfferCancelledEvent.php
index 995154a9d..aed51d73d 100644
--- a/src/Mealz/MealBundle/Event/MealOfferCancelledEvent.php
+++ b/src/Mealz/MealBundle/Event/MealOfferCancelledEvent.php
@@ -20,7 +20,7 @@ public function __construct(Participant $participant)
         $this->participant = $participant;
     }
 
-    public function getMeal(): Meal
+    public function getMeal(): ?Meal
     {
         return $this->participant->getMeal();
     }
diff --git a/src/Mealz/MealBundle/Event/MealOfferedEvent.php b/src/Mealz/MealBundle/Event/MealOfferedEvent.php
index a37f5b1c6..fac46002f 100644
--- a/src/Mealz/MealBundle/Event/MealOfferedEvent.php
+++ b/src/Mealz/MealBundle/Event/MealOfferedEvent.php
@@ -17,7 +17,7 @@ public function __construct(Participant $participant)
         $this->participant = $participant;
     }
 
-    public function getMeal(): Meal
+    public function getMeal(): ?Meal
     {
         return $this->participant->getMeal();
     }
diff --git a/src/Mealz/MealBundle/Resources/config/routing.yml b/src/Mealz/MealBundle/Resources/config/routing.yml
index cdf10aae6..fae823953 100644
--- a/src/Mealz/MealBundle/Resources/config/routing.yml
+++ b/src/Mealz/MealBundle/Resources/config/routing.yml
@@ -187,6 +187,16 @@ MealzMealBundle_api_events_delete:
   defaults: { _controller: App\Mealz\MealBundle\Controller\EventController::delete }
   methods: [ DELETE ]
 
+MealzMealBundle_api_events_join:
+  path: /api/events/participation
+  defaults: { _controller: App\Mealz\MealBundle\Controller\EventController::join }
+  methods: [ POST ]
+
+MealzMealBundle_api_events_leave:
+  path: /api/events/participation
+  defaults: { _controller: App\Mealz\MealBundle\Controller\EventController::leave }
+  methods: [ DELETE ]
+
 MealzMealBundle_Meal_offers:
     path: /menu/{date}/{dish}/offers
     defaults: { _controller: App\Mealz\MealBundle\Controller\MealController::getOffers }
diff --git a/src/Mealz/MealBundle/Service/Doorman.php b/src/Mealz/MealBundle/Service/Doorman.php
index f1ef7c2c2..5c77570e9 100644
--- a/src/Mealz/MealBundle/Service/Doorman.php
+++ b/src/Mealz/MealBundle/Service/Doorman.php
@@ -2,6 +2,7 @@
 
 namespace App\Mealz\MealBundle\Service;
 
+use App\Mealz\MealBundle\Entity\EventParticipation;
 use App\Mealz\MealBundle\Entity\Meal;
 use App\Mealz\MealBundle\Entity\Participant;
 use App\Mealz\UserBundle\Entity\Profile;
@@ -66,6 +67,15 @@ public function isUserAllowedToJoin(Meal $meal, array $dishSlugs = []): bool
                 && $this->hasAccessTo(self::AT_MEAL_PARTICIPATION, ['meal' => $meal]);
     }
 
+    public function isUserAllowedToJoinEvent(EventParticipation $eventParticipation): bool
+    {
+        if (false === $this->security->getUser()->getProfile() instanceof Profile) {
+            return false;
+        }
+
+        return $this->isToggleParticipationAllowed($eventParticipation->getDay()->getLockParticipationDateTime());
+    }
+
     public function isOfferAvailable(Meal $meal): bool
     {
         if (false === $this->security->getUser()->getProfile() instanceof Profile) {
diff --git a/src/Mealz/MealBundle/Service/EventParticipationService.php b/src/Mealz/MealBundle/Service/EventParticipationService.php
index 6af20fbe5..5e990664e 100644
--- a/src/Mealz/MealBundle/Service/EventParticipationService.php
+++ b/src/Mealz/MealBundle/Service/EventParticipationService.php
@@ -5,6 +5,7 @@
 use App\Mealz\MealBundle\Entity\Day;
 use App\Mealz\MealBundle\Entity\Event;
 use App\Mealz\MealBundle\Entity\EventParticipation;
+use App\Mealz\MealBundle\Entity\Participant;
 use App\Mealz\MealBundle\Repository\EventParticipationRepositoryInterface;
 use App\Mealz\MealBundle\Repository\EventRepositoryInterface;
 use App\Mealz\UserBundle\Entity\Profile;
@@ -12,15 +13,18 @@
 
 class EventParticipationService
 {
+    private Doorman $doorman;
     private EntityManagerInterface $em;
     private EventParticipationRepositoryInterface $eventPartRepo;
     private EventRepositoryInterface $eventRepo;
 
     public function __construct(
+        Doorman $doorman,
         EntityManagerInterface $em,
         EventRepositoryInterface $eventRepo,
         EventParticipationRepositoryInterface $eventPartRepo
     ) {
+        $this->doorman = $doorman;
         $this->em = $em;
         $this->eventPartRepo = $eventPartRepo;
         $this->eventRepo = $eventRepo;
@@ -55,6 +59,36 @@ public function getEventParticipationData(Day $day, Profile $profile): ?array
         ];
     }
 
+    public function join(Profile $profile, Day $day): ?EventParticipation
+    {
+        $eventParticipation = $day->getEvent();
+        if (null !== $eventParticipation && true === $this->doorman->isUserAllowedToJoinEvent($eventParticipation)) {
+            $participation = $this->createEventParticipation($profile, $eventParticipation);
+            if (null !== $participation) {
+                $this->em->persist($participation);
+                $this->em->flush();
+
+                $eventParticipation->addParticipant($participation);
+
+                return $eventParticipation;
+            }
+        }
+
+        return null;
+    }
+
+    public function leave(Profile $profile, Day $day): ?EventParticipation
+    {
+        $eventParticipation = $day->getEvent();
+        $participation = $eventParticipation->getParticipant($profile);
+
+        $eventParticipation->removeParticipant($participation);
+        $this->em->remove($participation);
+        $this->em->flush();
+
+        return $eventParticipation;
+    }
+
     private function addEventToDay(Day $day, ?Event $event)
     {
         // new eventparticipation
@@ -74,4 +108,9 @@ private function removeEventFromDay(Day $day)
             $day->setEvent(null);
         }
     }
+
+    private function createEventParticipation(Profile $profile, EventParticipation $eventParticiation): ?Participant
+    {
+        return new Participant($profile, null, $eventParticiation);
+    }
 }
diff --git a/src/Mealz/MealBundle/Service/ParticipationServiceTrait.php b/src/Mealz/MealBundle/Service/ParticipationServiceTrait.php
index 204b677ae..157e14f3d 100644
--- a/src/Mealz/MealBundle/Service/ParticipationServiceTrait.php
+++ b/src/Mealz/MealBundle/Service/ParticipationServiceTrait.php
@@ -104,7 +104,7 @@ private function slotIsAvailable(Slot $slot, DateTime $date): bool
      */
     private function createParticipation(Profile $profile, Meal $meal, ?Slot $slot = null, array $dishSlugs = []): Participant
     {
-        $participant = new Participant($profile, $meal);
+        $participant = new Participant($profile, $meal, null);
         if (null !== $slot) {
             $participant->setSlot($slot);
         }