Two summers ago, Dave Chappelle was receiving his high school diploma from the Duke Ellington School of the Arts, right here in Washington. This summer the comedian is back in town -- at a theater near you. He has a role in Mel Brooks's "Robin Hood: Men in Tights."

Quite a stretch.

He still looks 19, but he jokes with the insight, timing and polish of a comic many years his senior. Doing stand-up, Chappelle works the room with observational vignettes that mine the humor in everyday black-white relations: "I took two white friends of mine to see 'Malcolm X.' They were in shock. Mouths hanging open. They had no idea that black people like to talk at the movies." He's got the pointedness of Richard Pryor and the poignancy of Bill Cosby, two of his heroes.

But Chappelle's observations aren't confined to generating laughs in the spotlight. As show business success broadens his vision, he's getting a new perspective on where he came from and where he's headed.

"It's sad going home sometimes," he sighs long-distance from Los Angeles. "When I lived there I remember a limited feeling, almost a feeling of desperation to get out of D.C. All my buddies got out of there. We all moved to New York. ... It used to amaze me that I would get jaywalking tickets in Georgetown when there's all that stuff going on in my neighborhood. It's like, 'Well, let's keep the white neighborhoods safe at least.' "

His last visit to Washington was at Christmastime. "Now when I go home I see what I love -- my mom, my grandma. All the peer pressure, the drugs, that stuff just seems behind me, even though it's around me. Like in high school, it used to be all the football players got all the girls -- now all the drug dealers do."

Chappelle's is one of those overnight success stories that took years to happen. He found his calling at age 14. "It hit me like a revelation, man, I'm not lying. I didn't think I could do anything -- I was a mediocre basketball player, a bad student -- and all of a sudden I realized I could make money being funny."

Which brings us to Bill Cosby. "I read this article on Cosby in Time magazine called 'Funny, 50 and Filthy Rich,' and then I bought a book about him," Chappelle says, memories of dollar signs flashing in his voice. There were many similarities between funny man and funny boy. "He was a bad student -- hey, I'm a bad student. The kids thought he was funny -- well, the kids think I'm funny. And this guy made a million-dollar career out of being funny."

Chappelle took to the stage in local clubs -- Garvin's, the Comedy Cafe, the Comedy Connection -- and in case you're wondering how a kid barely out of junior high had the maturity to handle nightclub audiences, here's your answer:

"I think I was sort of advanced because of the way I was raised. My parents always treated me, to an extent, like an adult," he says. "I had the kind of parents who didn't have to beat me, but if they were to say something like, 'Oh, I'm very disappointed in you,' that would hurt, 'cause I revered them. They had that kind of control on me -- they could let me go to a comedy club when I was 14 and trust the fact that I wouldn't get into anything ridiculous."

It was the local comics -- guys such as Andy Evans, Andy Woods and the Fat Doctor -- who influenced Chappelle the most, in action and in deed. "I would look at the comedians in D.C., how they were all just trapped there," he says. "They made their money, they were comfortable, and that was it. They were always talking about doing better things, but they never did 'em."

They also gave him some advice. "They would pull me aside and say, 'You're 14, you shouldn't tell a lot of dirty stuff, because what do you know? Even if you do know something, you don't look like you know anything.' "

To curse or not to curse is a choice every comedian must make, and Chappelle usually stays on the clean side. "I've never been a dirty comic," he states. "I don't really have dirty thoughts. Well, I have some, but none that I talk about onstage. I'm not ready to be that honest."

Some crowds expect it, however, and for an appearance on HBO's "Def Comedy Jam," Chappelle gave in. "I didn't know {the show} was going to be as huge as it was," he says. "I kind of regret being dirty on the show. If I had known so many people were watching I might have represented myself differently."

"Def Comedy Jam" has become a major showcase for black comedians, and though Chappelle admits there are "a lot of positive things to the show," he sees a negative side too. "It kind of changed a lot of things for black comics, where now both black and white people expect you to be dirty. ... It's not fair, man, because now it's limiting everyone."

But this young man is not one to limit himself. When the chance came to appear in "Robin Hood," he jumped. "I auditioned in New York, they put me on tape, sent it out to L.A.," he explains. "Two or three days later I was in Mel Brooks's office." Without having gone through the entire script -- "I didn't think I'd make it that far" -- he read cold for the director in the morning and was given the part of Ahchoo that night.

Chappelle was already a fan. "I'd seen 'Young Frankenstein' and 'History of the World,' and when I rented 'Blazing Saddles' on video I really appreciated him."

So what's Mel Brooks like?

"Hysterical," Chappelle says with reverence. "And real, real approachable. He'd sit me down and teach me how to make movies. Here's a guy that's been in Hollywood all these years, and he's not pretentious at all. To me, that shows tremendous strength of character."

Most families want nothing more than for their offspring to succeed, and Chappelle is keeping them smiling back home. "They're just happy to see me in the movie. They were so scared when I didn't go to college. Especially my grandmother. I was the first person in my family not to go to college -- there were escaped slaves in my family that went to school."

In September Chappelle will fly to Scotland for an appearance in the Edinburgh Comedy Festival. He appeared in, then was edited out of, an upcoming film starring Dennis Quaid and Kathleen Turner, and did a television pilot for Disney that wasn't picked up. Of course, he still got paid. And he's still got his dreams of a Cosbyesque sitcom and writing his own movies.

Will success spoil the mediocre basketball player?

"I keep my same friends. It's funny how many people pop up when your income increases -- and I don't know how people know, but they just know," he says. Chappelle seems genuinely awed by and wary of the Hollywood snake pit he's stepping into. "This is the first time in my life I've ever had to think about things like that. I never had money, or the kind of looks that women would sleep with me for. Now all of a sudden -- kaboom!"