I think it depends on their maturity level, not necessarily their age. By the time I was online, I was mature enough not to get into any trouble, but I was also mature for my age and not very net-adventurous. Whereas my boyfriend was apparently a little online trouble maker at a later age and should have been more supervised. Also, are we talking overt supervision (ie, parent beside the computer as you surf) or covert supervision (ie, net nanny or some other program to log where the children go)? I would say covert supervision should go on long after overt supervision if for no other reason than you should still be supervising them, but they’ll be super annoyed with it and you if you are literally standing behind them. edit: I was very adventurous, I just wasn’t into causing trouble.