The teenager sitting on the stool is Marcus Thomas, a would-be boxer trying to work out a new life after a conviction for dealing cocaine. His teenage years were rough, as he came of age in Southeast Washington while his mother was dying of cancer and the streets were filled with the quick-money temptations of the drug trade.

Now he's 18. He has no high-school diploma, no immediate family, no car, not much money and a juvenile record, having spent time at the Oak Hill Youth Center, the city's youth detention home.

"The biggest problem isn't always on the street," Thomas is saying. "The biggest problem is yourself, your attitude, the way you handle things. . . . I wasn't using drugs, but I was selling them. I was being ignorant like everybody else."

He's talking to the man on the couch, Marc Bell, director of advocacy programs for the Center on Juvenile and Criminal Justice, a nonprofit agency that works to keep troubled kids like Thomas out of jail.

This is a familiar conversation for Bell, 34, because 16 years ago he was also a teenager with a short history of arrests and a conviction for dealing drugs. Like Thomas, he grew up in Southeast Washington, got caught up in the street trade and found himself in a youth detention center, staring at a dead-end career of more arrests and more jail time.

"I just wanted to live the image of 'Scarface,' " Bell remembers, citing the Al Pacino film about a cocaine drug lord. "When they locked me up, I realized I wasn't going anywhere, literally or figuratively. I just couldn't accept that for myself."

But Bell defied the stereotype of a young black man from Southeast in trouble with the law. He quit the lifestyle, graduated from high school, received an undergraduate degree from Morgan State University and, last week, obtained a master's degree in social work from the University of Maryland.

He sees the same sort of potential in Thomas, a young man who might go either way.

"What we need," he tells Thomas, "is more brothers like you in college."

Like a growing cadre of African American men incarcerated during the drug wars of the late 1980s and 1990s, Bell has returned to his old stomping grounds to help the next generation. It's behind-the-headlines work with teenagers who often have more attitude than aspirations, but his work is paying quiet dividends.

Bell's mentoring program has pulled more than 700 kids facing criminal charges out of detention in the last seven years, put them back in the community under close monitoring and kept 85 percent of them from violating the terms of their release.

In the District, where more than one in three black men are under some arm of the criminal justice system, that dose of stability is a key opportunity for Bell and his peers to show their young charges that there is life after jail.

"A lot of these kids are caught in thinking that they can get by just looking good and talking slick," he said. "You have to break it down for them that even if they get some job paying $10 per hour, you're never going to get out of the life. You have to change their thinking about education, about what's possible for themselves."

About 91,000 teenagers are in detention centers or jails across the country on any given day, according to the Justice Department. In the District, where youth detention centers have been overcrowded for years, an entire generation has come of age with firsthand experience of arrest and incarceration.

Bell's program, funded by the Youth Services Administration and officially known as the Intensive Third Party Mentoring Program, works to get some of those teens out of jail and back into their homes, where the plan is for them to sort out their troubles in a more stable surrounding.

The target population are the kind of teenagers who violate the law but don't get in the headlines for dramatic or especially violent crimes. To qualify for the program, they must be 14 to 21 years old and facing less violent charges, such as drug dealing or burglary. They must have some sort of home environment where they can stay, even if it's with a guardian or an older member of their extended family.

If their case is approved by a D.C. Superior Court judge or their social worker, the youths leave Oak Hill and return to their homes. Case workers check on them three times a day for weeks, put them in specialized schools, counseling sessions, job placement classes, substance abuse programs and impose a 9 p.m. or 10 p.m. curfew.

The program costs about $34 a day for each teenager enrolled, as opposed to an average daily cost of $166 for juveniles detained at Oak Hill.

Bell's group receives about $450,000 a year from the city. But the money is allocated on a month-to-month basis, and he is seeking additional funding to provide a more stable revenue source.

There is a separate program for young men over 18, such as Thomas, who show promise but have no place to stay. The program is a good deal for him, paying his $450 monthly rent and giving him a $91 weekly stipend, but only if he keeps his job at a Head Start day care center, goes to classes to get his general equivalency diploma and meets regularly with his counselors.

Bell's organization has put together similar programs in Hawaii and California, drawing positive evaluations from the Justice Department and the American Correctional Association.

Stephanie Payton, 16, a District resident who was arrested for selling drugs, attended a six-week class to help her earn the equivalent of a high school degree, and she received a $100 weekly stipend and a $50 bonus for not missing a day of class.

"She's a bright girl, but she can be very difficult," said Pamela Payton, her mother. "The counselor found a school program for her, and she finally felt she was listened to, that they treated her like an adult. She's got something good going for her right now."

Youths like Payton and Thomas often come before Judge Reggie B. Walton, presiding judge of the family division in D.C. Superior Court. Walton knows their problems because he had to overcome his own teenage arrests before moving on to a career on the bench and in government.

"The unfortunate reality is that a lot of the kids who come into court don't need to be detained or jailed, but they don't have the stabilizing and disciplinary forces in their lives to help them settle down at home," he said. "As a judge, you're left with the question of where to put them. That's where programs like this come in, to give kids who might make it a chance to do so, and to keep them out of jail."

Bell, who is developing a similar program in Baltimore, is convinced that most teenagers filling detention centers across the country don't need to be incarcerated. In the District, where almost all youths who wind up in Oak Hill are black or Hispanic, he said that the system is too quick to give up on difficult minority children, like himself a few years ago.

"A lot of these kids can make it if they just have the right kind of support," he said. "If we can help a 14-year-old to stay out of trouble, how many years of potential criminal behavior is that saving this neighborhood?"

Bell, who now counsels troubled young men, was convicted of drug dealing as a teenager.Marc Bell, a mentor for troubled teenagers, center, talks with Marcus Thomas, left. With them is Thomas's case worker, Calvin Smith.