In a 19th century oak-paneled dining room, before a long table set with sterling silver, 75 drug addicts jostled for standing room.

All eyes were fixed on a small woman with a broad, ironic smile. "Good afternoon," Mimi Silbert said. The group returned the greeting in unison, and then broke into laughter. Silbert, president of the Delancey Street Foundation drug rehabilitation program, was already playing the room like a violin.

The surroundings -- a Tudor-style mansion set in 92 wooded acres about 70 miles north of New York City -- seemed impossibly opulent for a drug treatment program. But they reflected Delancey Street's style, as well as its success at turning drug problems into manpower, all the while shunning government money.

The money that residents make selling stenciled coffee mugs to university bookstores, moving furniture with Delancey's fleet of trucks, or building ornamental planters at the foundation's factory puts food on the table -- and working capital into the foundation's budget. In turn, addicts and criminals get a taste of what it's like to lead a normal, workaday life.

Nearly one of every three residents here was convicted in D.C. Superior Court of selling drugs, prostitution or violent crimes such as robbery or assault. They were placed on probation to come to Brewster, and before they are deemed ready to return to society, most will spend at least four years in one of three Delancey facilities in California and New Mexico, or in this 30-room, renovated castle.

During that time, they are supposed to learn to read and write; cook a meal or lay bricks; drive a truck or keep books. When they sit down to dinner, there might be oysters or snails on their plates. Silbert contends that exposure to the finer and more exotic things in life takes some of the fear out of being an addict, fear of a larger world that for them seems full of complications and problems too big to overcome without using drugs.

"Our people who stay here have to do four years just like Harvard," said Silbert, 44, a criminologist and psychologist who once counseled offenders at Lorton Reformatory's Youth Center. "Never Learned to Make Their Way"

"We're dealing with a lot of people who have never learned to make their way legitimately or successfully into American society. We teach them how to do it on the assumption that you can then reject anything in society you don't like, but not because you don't know about it."

Each morning there is a new vocabulary word to learn -- "ghetto talk" is strictly prohibited. Breakfast call comes at 7:30 a.m., and for the rest of the day it's work at one of the several industries, supervised by more experienced residents.

At Delancey's four facilities there is only one paid employe: Silbert. The rest of the job of managing the foundation's properties and businesses is left to the residents themselves, the most successful of whom move to the top of the Delancey hierarchy and the most coveted rewards, a private room and dating privileges.

The 23 D.C. convicts at Brewster, many of them unable to get into packed programs near Washington, found out about Delancey Street through their attorneys or from the brochures the foundation sends to the D.C. Jail.

Most graduates go on to lead successful lives, Silbert said, because they must have three skills and a job before they leave. So far, though, none of the D.C. enrollees has been in the program long enough to graduate.

Started in San Francisco by four addicts 15 years ago with a $1,000 loan, Delancey Street prefers to take serious criminals, rejecting only sex offenders. Silbert said she joined the group after being asked to help write a proposal for a government grant, and later took full charge. She tries to accept all who apply, although she has had to close the doors to some in the past year because of a crush of applicants.

Melvin Peoples, a 32-year-old heroin addict and drug peddler, took the train to Brewster from Washington last year after a Superior Court judge placed him on probation following Peoples' guilty plea to a charge of trying to kill his wife.

"I didn't know where to go," said Peoples, who was turned away from at least three programs in Washington. "Either they were full up or they wouldn't accept me."

Now he is helping to install electrical wiring at the expanding Brewster complex, aiming to become a master electrician. "I'd been in it [drugs] for a long time. And this has given me a chance to see the other side, how it is without any heroin, without the craziness of the streets."

Joe Henery, 39, who grew up around 14th and U streets NW, was peddling drugs and stealing purses out of offices to support his addiction when he was caught driving a stolen car. He was placed on probation to enter Delancey Street last year and said he sees this as his last, best chance to go straight. He's got a carpentry job, turning one of the estate's outbuildings into an office.

"If I had gotten out of jail this time instead of coming to Delancey Street, . . . I probably would be dead or so far gone until wouldn't nobody even like to have anything to do with me." Residents Attend Free

In all, Silbert oversees more than $7 million in property and other assets and $6 million in income last year, according to a financial statement she provided. Residents attend the program free of charge.

The foundation was named for a street on New York's Lower East Side that was a haven for immigrants at the turn of the century. Silbert said she adopted many of the ideas for Delancey's self-supporting industries from what she saw while visiting an Israeli kibbutz.

She sees addicts as people trapped in a cycle of guilt, self-hatred and destructive behavior who don't know how to cope or live with other people and who desperately need to learn traditional American values.

The surroundings at Brewster might be lush, but residents, she maintains, are doing more penance than if they were locked in a cell. They must finally take responsibility for their lives.

"Prison does not give anyone a sense of responsibility. It's the exact opposite," she said. "You see a cell in the prison system and it's disgusting, but it's not necessarily the hardest punishment for a person coming from a world these people have come from.

"Our punishment is much worse. It's that you work."