He began smoking marijuana late in life, the student says, late compared to some of his peers who began in elementary school.

In 10th grade at Bethesda-Chevy Chase High School, he tried his first joint. In 11th grade, he began dealing marijuana regularly.

"You realize that it's [marijuana] something most everyone in school is interested in, and that money is passed around to get it," he says, nervously drumming his fingers on a brick wall. "It's like any business principle, dependent on supply and demand."

The young man, who lives in Chevy Chase and comes from an upper-middle-class family, "not terribly rich, not poor," graduated from B-CC yesterday His parents know he smokes marijuana, but have no idea he sells it, he says.

Although he made more than $2,000 this year selling marijuana, he and most other dealers at B-CC see the business as a way to get free dope - "we end up smoking most of our profits" - and have a little spending change on the side.

He got into the business by taking $400 that he had saved from a summer job, and purchasing a pound of marijuana from a student wholesaler.

"Most of the time I buy from the wholesalers in other parts of the area," he says."It's like contacts in other business. You have friends who have friends who have other friends in the trade. I have about four steady wholesalers I buy from, mainly at colleges: Montgomery College, Maryland and Georgetown.

"The first pound I bought was from another B-CC student," he says, lowering his voice as a mailman walks by. "I learned not to do it again. We arranged to make the exchange at school, but here comes this guy walking down the hall with a pound of weed in a paper bag. If you're smart, you're not obvious."

He broke the pound into quarter-ounce, half-ounce, and ounce sizes. He then resold the marijuana that he had bought for $25 an ounce for $40 an ounce. Within two weeks, he says, he had sold the entire pound. His original $400 investment had become $640.

The transfers were made, he says, in secluded and not-so-secluded spots around school. Bathrooms, surrounding fields, hallways, classrooms, and at weekend parties.

"Usually you buy a quarter-pound . . . because one pound is an awful lot to handle," he says. "The demand happened to be pretty high when I sold it, so it didn't take very long."

His wholesalers were generally persons in their 20s, he says. Some were college students; others worked full time at regular jobs and earned additional money selling marijuana on the side.

"There's one guy I know in Georgetown who doesn't go to school or work," he confides. "He does it [wholesailing] full time. He lives in humble circumstances but it's a front. I know he's got thousands stashed away in the bank."

Wholesalers in harder drugs usually go to New York for connection, the B-CC dealer says, but most marijuana wholesalers get their from ships smuggling it up the Potomac River or into the Chesapeake Bay. He recalled the April police raid on a sailboat on the Potomac River near Indian Head, Md., in which three tons of marijuana were seized.

"I wouldn't be all surprised," he said, "if some of that herb was headed for Montgomery."

Hawaiian marijuana is the most potent and expensive, he says, going for between $100 and $220 an ounce. His biggest deal was consummated last winter when, one day before school, he sold 2 1/2 ounces of Hawaiian for $500.

He keeps meticulous books at home on his purchases and sales. "When you are in business seriously, you have to do it businesslike," he says. This past year, he bought more than $2,000 worth of marijuana and earned more than $2,000 in profits.

"I've only got about a thousand in the bank," he says. "The rest I've used as spending change or smoked."

But despite the big profits in dealing, B-CC's biggest dealer doesn't think he wants to get any deeper into the world of dope smuggling and wholesaling.

"The higher the amounts, the more the risk," he says. "You end up having to trust too many people."