diff --git a/geneit_backend/src/controllers/families_controller.rs b/geneit_backend/src/controllers/families_controller.rs
index f380f7d..95e1458 100644
--- a/geneit_backend/src/controllers/families_controller.rs
+++ b/geneit_backend/src/controllers/families_controller.rs
@@ -1,6 +1,7 @@
 use crate::constants::{StaticConstraints, FAMILY_INVITATION_CODE_LEN};
 use crate::controllers::HttpResult;
 use crate::extractors::family_extractor::{FamilyInPath, FamilyInPathWithAdminMembership};
+use crate::models::UserID;
 use crate::services::login_token_service::LoginToken;
 use crate::services::rate_limiter_service::RatedAction;
 use crate::services::{families_service, rate_limiter_service};
@@ -133,3 +134,38 @@ pub async fn renew_invitation_code(f: FamilyInPathWithAdminMembership) -> HttpRe
 pub async fn users(f: FamilyInPath) -> HttpResult {
     Ok(HttpResponse::Ok().json(families_service::get_memberships_of_family(f.family_id()).await?))
 }
+
+#[derive(serde::Deserialize)]
+pub struct UserIdInPath {
+    user_id: UserID,
+}
+
+#[derive(serde::Deserialize)]
+pub struct UpdateMembershipBody {
+    is_admin: bool,
+}
+
+/// Update a membership
+pub async fn update_membership(
+    f: FamilyInPathWithAdminMembership,
+    path: web::Path<UserIdInPath>,
+    req: web::Json<UpdateMembershipBody>,
+) -> HttpResult {
+    // An admin can not update his own membership
+    if path.user_id == f.user_id() {
+        return Ok(HttpResponse::Conflict().body("You cannot update your own membership!"));
+    }
+
+    let mut membership = families_service::get_membership(f.family_id(), path.user_id).await?;
+    membership.is_admin = req.is_admin;
+    families_service::update_membership(&membership).await?;
+
+    log::debug!(
+        "User {:?} updated the membership of user {:?} in the family {:?}",
+        f.user_id(),
+        path.user_id,
+        f.family_id()
+    );
+
+    Ok(HttpResponse::Accepted().finish())
+}
diff --git a/geneit_backend/src/main.rs b/geneit_backend/src/main.rs
index a0b27d1..23848ee 100644
--- a/geneit_backend/src/main.rs
+++ b/geneit_backend/src/main.rs
@@ -114,6 +114,10 @@ async fn main() -> std::io::Result<()> {
                 "/family/{id}/users",
                 web::get().to(families_controller::users),
             )
+            .route(
+                "/family/{id}/user/{user_id}",
+                web::patch().to(families_controller::update_membership),
+            )
     })
     .bind(AppConfig::get().listen_address.as_str())?
     .run()
diff --git a/geneit_backend/src/models.rs b/geneit_backend/src/models.rs
index 4c24ead..1041c43 100644
--- a/geneit_backend/src/models.rs
+++ b/geneit_backend/src/models.rs
@@ -2,7 +2,7 @@ use crate::schema::{families, memberships, users};
 use diesel::prelude::*;
 
 /// User ID holder
-#[derive(Debug, Clone, Copy, serde::Serialize, serde::Deserialize)]
+#[derive(Debug, Clone, Copy, serde::Serialize, serde::Deserialize, PartialEq, Eq)]
 pub struct UserID(pub i32);
 
 #[derive(Queryable, Debug, serde::Serialize)]
diff --git a/geneit_backend/src/services/families_service.rs b/geneit_backend/src/services/families_service.rs
index 2a00354..85bc6bc 100644
--- a/geneit_backend/src/services/families_service.rs
+++ b/geneit_backend/src/services/families_service.rs
@@ -107,6 +107,23 @@ pub async fn get_membership(family_id: FamilyID, user_id: UserID) -> anyhow::Res
     })
 }
 
+/// Update a membership to a family
+pub async fn update_membership(membership: &Membership) -> anyhow::Result<()> {
+    db_connection::execute(|conn| {
+        diesel::update(
+            memberships::dsl::memberships.filter(
+                memberships::dsl::user_id
+                    .eq(membership.user_id().0)
+                    .and(memberships::dsl::family_id.eq(membership.family_id().0)),
+            ),
+        )
+        .set(memberships::dsl::is_admin.eq(membership.is_admin))
+        .execute(conn)
+    })?;
+
+    Ok(())
+}
+
 #[derive(serde::Serialize)]
 pub struct FamilyMember {
     #[serde(flatten)]