I think that’s a WONDERFUL idea!! And you should agree to “match” his savings — perhaps dollar for dollar, or even more (up to the total amount of his earnings is eligible). I’d just go to Fidelity or Vanguard and open the account. Buy the S&P 500 stock index fund. This is not a place for him to start “trading” on ideas he’s had. But if he gets involved in following the market, you could open another account for him at Stockpile.com, and let him try investing in individual stocks with any extra money after his Roth IRA contribution.