I was about 11 when I joined the game originally, but, because the game is targeted for a 13+ audience, I'd say younger users should join at their own discretion. If their parents prefer to monitor their online experiences, then I'd suggest they take a look over the rules, but take it with a grain of salt, because not everything will be caught (considering the moderators are humans, and this is not some huge corporate run game with a team of 50+ mods). Especially because with certain groups, there is swearing and more "mature" themes involved. So again, at their own discretion.