Early marine basic - Page 2

July 13th, 2005  
You can join active duty at 17. This is an option for kids whose birthdays fall after their HS graduation date. IE you graduate in May, but your 18th birthday isn't until September. You'll need your parents signature to join.

As 03 has already said, if you want to take the split option route (finish bootcamp the summer prior to your senior year and MOS the summer after) you will have to join the Reserves.