diff --git a/lib/mobilizon_web/api/events.ex b/lib/mobilizon_web/api/events.ex
index 5e138eef8..45e107022 100644
--- a/lib/mobilizon_web/api/events.ex
+++ b/lib/mobilizon_web/api/events.ex
@@ -12,28 +12,69 @@ defmodule MobilizonWeb.API.Events do
   Create an event
   """
   @spec create_event(map()) :: {:ok, Activity.t(), Event.t()} | any()
-  def create_event(
-        %{
-          begins_on: begins_on,
-          description: description,
-          options: options,
-          organizer_actor_id: organizer_actor_id,
-          tags: tags,
-          title: title
-        } = args
-      )
-      when is_map(options) do
-    with %Actor{url: url} = actor <-
-           Actors.get_local_actor_with_everything(organizer_actor_id),
-         physical_address <- Map.get(args, :physical_address, nil),
-         title <- String.trim(title),
-         visibility <- Map.get(args, :visibility, :public),
-         picture <- Map.get(args, :picture, nil),
-         {content_html, tags, to, cc} <-
-           Utils.prepare_content(actor, description, visibility, tags, nil),
+  def create_event(%{organizer_actor: organizer_actor} = args) do
+    with %{
+           title: title,
+           physical_address: physical_address,
+           visibility: visibility,
+           picture: picture,
+           content_html: content_html,
+           tags: tags,
+           to: to,
+           cc: cc,
+           begins_on: begins_on,
+           category: category,
+           options: options
+         } <- prepare_args(args),
          event <-
            ActivityPubUtils.make_event_data(
-             url,
+             organizer_actor.url,
+             %{to: to, cc: cc},
+             title,
+             content_html,
+             picture,
+             tags,
+             %{begins_on: begins_on, physical_address: physical_address, category: category, options: options}
+           ) do
+      ActivityPub.create(%{
+        to: ["https://www.w3.org/ns/activitystreams#Public"],
+        actor: organizer_actor,
+        object: event,
+        local: true
+      })
+    end
+  end
+
+  @doc """
+  Update an event
+  """
+  @spec update_event(map()) :: {:ok, Activity.t(), Event.t()} | any()
+  def update_event(
+        %{
+          organizer_actor: organizer_actor,
+          event: event
+        } = args
+      ) do
+    with %{
+           title: title,
+           physical_address: physical_address,
+           visibility: visibility,
+           picture: picture,
+           content_html: content_html,
+           tags: tags,
+           to: to,
+           cc: cc,
+           begins_on: begins_on,
+           category: category,
+           options: options
+         } <-
+           prepare_args(
+             args
+             |> update_args(event)
+           ),
+         event <-
+           ActivityPubUtils.make_event_data(
+             organizer_actor.url,
              %{to: to, cc: cc},
              title,
              content_html,
@@ -46,12 +87,60 @@ defmodule MobilizonWeb.API.Events do
                options: options
              }
            ) do
-      ActivityPub.create(%{
+      ActivityPub.update(%{
         to: ["https://www.w3.org/ns/activitystreams#Public"],
-        actor: actor,
+        actor: organizer_actor,
         object: event,
         local: true
       })
     end
   end
+
+  defp update_args(args, event) do
+    %{
+      title: Map.get(args, :title, event.title),
+      description: Map.get(args, :description, event.description),
+      tags: Map.get(args, :tags, event.tags),
+      physical_address: Map.get(args, :physical_address, event.physical_address),
+      visibility: Map.get(args, :visibility, event.visibility),
+      physical_address: Map.get(args, :physical_address, event.physical_address),
+      begins_on: Map.get(args, :begins_on, event.begins_on),
+      category: Map.get(args, :category, event.category),
+      options: Map.get(args, :options, event.options)
+    }
+  end
+
+  defp prepare_args(
+         %{
+           organizer_actor: organizer_actor,
+           title: title,
+           description: description,
+           options: options,
+           tags: tags,
+           begins_on: begins_on,
+           category: category,
+           options: options
+         } = args
+       ) do
+    with physical_address <- Map.get(args, :physical_address, nil),
+         title <- String.trim(title),
+         visibility <- Map.get(args, :visibility, :public),
+         picture <- Map.get(args, :picture, nil),
+         {content_html, tags, to, cc} <-
+           Utils.prepare_content(organizer_actor, description, visibility, tags, nil) do
+      %{
+        title: title,
+        physical_address: physical_address,
+        visibility: visibility,
+        picture: picture,
+        content_html: content_html,
+        tags: tags,
+        to: to,
+        cc: cc,
+        begins_on: begins_on,
+        category: category,
+        options: options
+      }
+    end
+  end
 end
diff --git a/lib/mobilizon_web/resolvers/event.ex b/lib/mobilizon_web/resolvers/event.ex
index 8a01b2cf0..d34402f0f 100644
--- a/lib/mobilizon_web/resolvers/event.ex
+++ b/lib/mobilizon_web/resolvers/event.ex
@@ -58,7 +58,8 @@ defmodule MobilizonWeb.Resolvers.Event do
       ) do
     # We get the organizer's next public event
     events =
-      [Events.get_actor_upcoming_public_event(organizer_actor, uuid)] |> Enum.filter(&is_map/1)
+      [Events.get_actor_upcoming_public_event(organizer_actor, uuid)]
+      |> Enum.filter(&is_map/1)
 
     # We find similar events with the same tags
     # uniq_by : It's possible event_from_same_actor is inside events_from_tags
@@ -150,7 +151,17 @@ defmodule MobilizonWeb.Resolvers.Event do
          {:has_event, {:ok, %Event{} = event}} <-
            {:has_event, Mobilizon.Events.get_event_full(event_id)},
          {:ok, _activity, _participant} <- MobilizonWeb.API.Participations.leave(event, actor) do
-      {:ok, %{event: %{id: event_id}, actor: %{id: actor_id}}}
+      {
+        :ok,
+        %{
+          event: %{
+            id: event_id
+          },
+          actor: %{
+            id: actor_id
+          }
+        }
+      }
     else
       {:has_event, _} ->
         {:error, "Event with this ID #{inspect(event_id)} doesn't exist"}
@@ -173,12 +184,33 @@ defmodule MobilizonWeb.Resolvers.Event do
   @doc """
   Create an event
   """
-  def create_event(_parent, args, %{context: %{current_user: _user}} = _resolution) do
-    with {:ok, args} <- save_attached_picture(args),
+  def create_event(
+        _parent,
+        %{organizer_actor_id: organizer_actor_id} = args,
+        %{
+          context: %{
+            current_user: user
+          }
+        } = _resolution
+      ) do
+    with {:is_owned, true, organizer_actor} <- User.owns_actor(user, organizer_actor_id),
+         {:ok, args} <- save_attached_picture(args),
          {:ok, args} <- save_physical_address(args),
-         {:ok, %Activity{data: %{"object" => %{"type" => "Event"} = _object}}, %Event{} = event} <-
-           MobilizonWeb.API.Events.create_event(args) do
+         args_with_organizer <- Map.put(args, :organizer_actor, organizer_actor),
+         {
+           :ok,
+           %Activity{
+             data: %{
+               "object" => %{"type" => "Event"} = _object
+             }
+           },
+           %Event{} = event
+         } <-
+           MobilizonWeb.API.Events.create_event(args_with_organizer) do
       {:ok, event}
+    else
+      {:is_owned, false} ->
+        {:error, "Organizer actor id is not owned by the user"}
     end
   end
 
@@ -186,19 +218,66 @@ defmodule MobilizonWeb.Resolvers.Event do
     {:error, "You need to be logged-in to create events"}
   end
 
+  @doc """
+  Update an event
+  """
+  def update_event(
+        _parent,
+        %{event_id: event_id} = args,
+        %{
+          context: %{
+            current_user: user
+          }
+        } = _resolution
+      ) do
+    with {:ok, %Event{} = event} <- Mobilizon.Events.get_event(event_id),
+         {:is_owned, true, organizer_actor} <- User.owns_actor(user, event.organizer_actor_id),
+         {:ok, args} <- save_attached_picture(args),
+         {:ok, args} <- save_physical_address(args),
+         {
+           :ok,
+           %Activity{
+             data: %{
+               "object" => %{"type" => "Event"} = _object
+             }
+           },
+           %Event{} = event
+         } <-
+           MobilizonWeb.API.Events.update_event(args) do
+      {:ok, event}
+    else
+      {:error, :event_not_found} ->
+        {:error, "Event not found"}
+    end
+  end
+
+  def update_event(_parent, _args, _resolution) do
+    {:error, "You need to be logged-in to update an event"}
+  end
+
   # If we have an attached picture, just transmit it. It will be handled by
   # Mobilizon.Service.ActivityPub.Utils.make_picture_data/1
   # However, we need to pass it's actor ID
   @spec save_attached_picture(map()) :: {:ok, map()}
   defp save_attached_picture(
-         %{picture: %{picture: %{file: %Plug.Upload{} = _picture} = all_pic}} = args
+         %{
+           picture: %{
+             picture: %{file: %Plug.Upload{} = _picture} = all_pic
+           }
+         } = args
        ) do
     {:ok, Map.put(args, :picture, Map.put(all_pic, :actor_id, args.organizer_actor_id))}
   end
 
   # Otherwise if we use a previously uploaded picture we need to fetch it from database
   @spec save_attached_picture(map()) :: {:ok, map()}
-  defp save_attached_picture(%{picture: %{picture_id: picture_id}} = args) do
+  defp save_attached_picture(
+         %{
+           picture: %{
+             picture_id: picture_id
+           }
+         } = args
+       ) do
     with %Picture{} = picture <- Mobilizon.Media.get_picture(picture_id) do
       {:ok, Map.put(args, :picture, picture)}
     end
@@ -208,7 +287,13 @@ defmodule MobilizonWeb.Resolvers.Event do
   defp save_attached_picture(args), do: {:ok, args}
 
   @spec save_physical_address(map()) :: {:ok, map()}
-  defp save_physical_address(%{physical_address: %{url: physical_address_url}} = args)
+  defp save_physical_address(
+         %{
+           physical_address: %{
+             url: physical_address_url
+           }
+         } = args
+       )
        when not is_nil(physical_address_url) do
     with %Address{} = address <- Addresses.get_address_by_url(physical_address_url),
          args <- Map.put(args, :physical_address, address.url) do
@@ -230,9 +315,15 @@ defmodule MobilizonWeb.Resolvers.Event do
   @doc """
   Delete an event
   """
-  def delete_event(_parent, %{event_id: event_id, actor_id: actor_id}, %{
-        context: %{current_user: user}
-      }) do
+  def delete_event(
+        _parent,
+        %{event_id: event_id, actor_id: actor_id},
+        %{
+          context: %{
+            current_user: user
+          }
+        }
+      ) do
     with {:ok, %Event{} = event} <- Mobilizon.Events.get_event(event_id),
          {:is_owned, true, _} <- User.owns_actor(user, actor_id),
          {:event_can_be_managed, true} <- Event.can_event_be_managed_by(event, actor_id),
diff --git a/lib/mobilizon_web/schema/event.ex b/lib/mobilizon_web/schema/event.ex
index 8cbed015e..5c9956a6a 100644
--- a/lib/mobilizon_web/schema/event.ex
+++ b/lib/mobilizon_web/schema/event.ex
@@ -234,6 +234,35 @@ defmodule MobilizonWeb.Schema.EventType do
       resolve(&Event.create_event/3)
     end
 
+    @desc "Update an event"
+    field :update_event, type: :event do
+      arg(:event_id, non_null(:integer))
+
+      arg(:title, :string)
+      arg(:description, :string)
+      arg(:begins_on, :datetime)
+      arg(:ends_on, :datetime)
+      arg(:state, :integer)
+      arg(:status, :integer)
+      arg(:public, :boolean)
+      arg(:visibility, :event_visibility)
+
+      arg(:tags, list_of(:string), description: "The list of tags associated to the event")
+
+      arg(:picture, :picture_input,
+        description:
+          "The picture for the event, either as an object or directly the ID of an existing Picture"
+      )
+
+      arg(:publish_at, :datetime)
+      arg(:online_address, :string)
+      arg(:phone_address, :string)
+      arg(:category, :string)
+      arg(:physical_address, :address_input)
+
+      resolve(&Event.update_event/3)
+    end
+
     @desc "Delete an event"
     field :delete_event, :deleted_object do
       arg(:event_id, non_null(:integer))
diff --git a/test/mobilizon_web/resolvers/event_resolver_test.exs b/test/mobilizon_web/resolvers/event_resolver_test.exs
index 077f2ec05..7aa69929e 100644
--- a/test/mobilizon_web/resolvers/event_resolver_test.exs
+++ b/test/mobilizon_web/resolvers/event_resolver_test.exs
@@ -58,6 +58,40 @@ defmodule MobilizonWeb.Resolvers.EventResolverTest do
                json_response(res, 200)["errors"]
     end
 
+    test "create_event/3 should check the organizer_actor_id is owned by the user", %{
+      conn: conn,
+      user: user
+    } do
+      another_actor = insert(:actor)
+
+      begins_on = DateTime.utc_now() |> DateTime.truncate(:second) |> DateTime.to_iso8601()
+
+      mutation = """
+          mutation {
+              createEvent(
+                  title: "come to my event",
+                  description: "it will be fine",
+                  begins_on: "#{begins_on}",
+                  organizer_actor_id: "#{another_actor.id}",
+                  category: "birthday"
+              ) {
+                title,
+                uuid
+              }
+            }
+      """
+
+      res =
+        conn
+        |> auth_conn(user)
+        |> post("/api", AbsintheHelpers.mutation_skeleton(mutation))
+
+      assert json_response(res, 200)["data"]["createEvent"] == nil
+
+      assert hd(json_response(res, 200)["errors"])["message"] ==
+               "Organizer actor id is not owned by the user"
+    end
+
     test "create_event/3 creates an event", %{conn: conn, actor: actor, user: user} do
       mutation = """
           mutation {
@@ -384,6 +418,100 @@ defmodule MobilizonWeb.Resolvers.EventResolverTest do
       assert json_response(res, 200)["data"]["createEvent"]["picture"]["url"]
     end
 
+    test "update_event/3 should check the event exists", %{conn: conn, actor: actor, user: user} do
+      mutation = """
+          mutation {
+              updateEvent(
+                  event_id: 45,
+                  title: "my event updated",
+              ) {
+                title,
+                uuid,
+                tags {
+                  title,
+                  slug
+                }
+              }
+            }
+      """
+
+      res =
+        conn
+        |> auth_conn(user)
+        |> post("/api", AbsintheHelpers.mutation_skeleton(mutation))
+
+      assert hd(json_response(res, 200)["errors"])["message"] == "Event not found"
+    end
+
+    test "update_event/3 should check the user is an administrator", %{
+      conn: conn,
+      actor: actor,
+      user: user
+    } do
+      event = insert(:event)
+
+      mutation = """
+          mutation {
+              updateEvent(
+                  title: "my event updated",
+              ) {
+                title,
+                uuid,
+                tags {
+                  title,
+                  slug
+                }
+              }
+            }
+      """
+
+      res =
+        conn
+        |> auth_conn(user)
+        |> post("/api", AbsintheHelpers.mutation_skeleton(mutation))
+
+      assert json_response(res, 200)["errors"] == nil
+    end
+
+    test "update_event/3 updates an event", %{conn: conn, actor: actor, user: user} do
+      event = insert(:event)
+
+      begins_on = DateTime.utc_now() |> DateTime.truncate(:second) |> DateTime.to_iso8601()
+
+      mutation = """
+          mutation {
+              updateEvent(
+                  title: "my event updated",
+                  description: "description updated",
+                  begins_on: "#{begins_on}",
+                  organizer_actor_id: "#{actor.id}",
+                  category: "birthday",
+                  tags: ["tag1_updated", "tag2_updated"]
+              ) {
+                title,
+                uuid,
+                tags {
+                  title,
+                  slug
+                }
+              }
+            }
+      """
+
+      res =
+        conn
+        |> auth_conn(user)
+        |> post("/api", AbsintheHelpers.mutation_skeleton(mutation))
+
+      assert json_response(res, 200)["errors"] == nil
+      assert json_response(res, 200)["data"]["updateEvent"]["title"] == "my event updated"
+
+      assert json_response(res, 200)["data"]["createEvent"]["tags"] == [
+               %{"slug" => "tag1_updated", "title" => "tag1_updated"},
+               %{"slug" => "tag2_updated", "title" => "tag2_updated"}
+             ]
+    end
+
     test "list_events/3 returns events", context do
       event = insert(:event)