If he's a good student and has the time - - all the more reason for him to start working and start learning the value of money, how to be responsible, how to get along with co-workers, and a slew of other benefits one gets from joining the working world. Not to mention that if he finds a job he likes and does well at, his self-esteem will jump a few notches!
I also encourage my teens to do volunteer work (through the school, city, church or synagogue, local community center, etc.) - besides the great feeling of contribution and satisfaction they will get from helping someone, it's often a "door" into a job-opening on the spot, a great reference for a resume, and a way to explore what their longterm interests may be.
(and I AM biased - my first ever jobs were the result of volunteer positions!)
-Tamara