{ "rules": { ".read": true, "users": { "$user": { //can add a message if authenticated ".write": "auth.uid === $user" } }, "rooms": { "$room": { "users": { // can write to the users list only if ADMINISTRATOR "$user": { "write":"newData.parent().child(auth.uid).val() === 99" } } } }, "messages": { "$room": { "$message": { //can add a message if they are a MEMBER ".write": "(!data.exists() && newData.exists() && root.child('rooms/' + $room + '/users/' + auth.uid).val() >= 10)" } } } } }