Forget yuppies. It's their little brothers and sisters you want.

At least that's the message Harvard graduate students Lawrence Graham and Lawrence Hamdan think more companies need to hear. In 1984, the two entrepreneurs got fed up with seeing wealthy baby boomers overrepresented in ads. So they dubbed the Y-people's 13-to-25-year-old siblings "flyers" (Fun Loving Youth En Route to Success), and formed F.L.Y.E.R.S. Services Inc. to tell marketers how to reach them.

The pair's perspective in all this isn't entirely objective. Part of the expertise that Graham, 23, and Hamdan, 24, claim to have developed on the preferences of flyers comes from personal experience. They back that with a national network of 135 young testers who survey their peers.

On the surface, choosing these times to target the youth market seems wrong-headed. The older baby-boomer crowd dwarfs today's younger generation in size. Not only that, but flyers aren't af affluent as yuppies. Most don't work full-time -- and those who do usually hold low-paying, entry-level jobs.

That, according to the Larrys, is just the point. While the upwardly mobile yuppies represent only a fraction of their generational head count, all young people are circumstantially united by their relatively small independent incomes. "At this time in their lives, these people share much more similar tastes and purchasing patterns" than they ever will again, Hamdan says. Yet whatever money flyers do have is usually disposable ($4,000 a year on average). And what they lack in individual income, they more than make up for in numbers (there are 50 million of them). As a result, they are a spending force of $200 billion a year. And because they're just beginning to establish brand loyalties, they're ready to the influenced.

How do flyers differ from their older siblings? According to Hamdan and Graham, they are more optimistic and less driven -- the result of having grown up without the turmoil of the 1960s and the competition only an oversize generation can cause. And, because far more of them have had two working parents and held part-time jobs when in high school, flyers are used to independence and responsibility at an early age. That may be good news for entrepreneurial companies seeking help, Hamdan says, because young people perceive smaller, growing firms as places where they can have flexibility and an impact.

Hamdan and Graham also think this independent generation will produce a large share of entrepreneurs -- and the two plan to be among them. Their latest book, Youth Trends, is Graham's eighth or ninth (he loses count). And since its founding, F.L.Y.E.R.S. Services has sold more than $250,000 worth of advice to clients such as Reader's Digest Association. All while its only two employees have been attending Harvard full-time. Not bad for an after-school job.