NEW YORK -- The frightening specter of homelessness is never far from Lyndia Bennett's universe -- a place where hopeless men guzzle booze out of bottles in brown-paper sacks, where dope dealers peddle drugs on appointed street corners, where empty vials of crack litter the sidewalks.

In her apartment in a yellow-brick Harlem tenement, there are holes in the doors and the floor is covered with a sprinkling of paint chips that looks like green confetti. Ammonia cannot mask the stink of urine in the stairwell.

But for the 34-year-old Ms. Bennett, who has known the ache of homelessness, there is no place like home, even this one.

As the numbers of homeless increase, government and private social service providers are beginning to expand dramatically their reach to try to catch the many thousands of ex-homeless, like Ms. Bennett and her five children, who are on the verge of becoming homeless again and falling back into the city's vast shelter system.

In New York, Baltimore, Washington and other cities that harbor large numbers of homeless, programs are being formed to link the ex-homeless with services -- substance abuse programs, day-care centers, financial advisers, among them -- in an effort to overcome the problems that have thrown their housing into jeopardy. Even the federal government has begun to shift its emphasis from emergency shelters to services.

"Clearly, a shift in thinking has occurred," said Anna Kondratas, an assistant secretary of the U.S. Department of Housing and Urban Development. "What we hope to see at the local level is a shift toward permanent solutions.

"Part of the reason it's taken so long is throughout most of the 1980s the advocates emphasized the emergency shelter needs of the homeless. People believed [National Coalition for the Homeless founder] Robert Hayes when he said: 'All you need to end homelessness is housing, housing, housing.' There was a misdefinition of how complex the problem was."

For Ms. Bennett, the threat of repeat homelessness surfaced two months ago when her landlord notified her that the rent, now $349, would rise by $170 a month when her lease expires this spring. Since then, an advocate with the after-care unit of Homes for the Homeless, a non-profit New York shelter provider, has stepped in to assist Ms. Bennett in keeping her apartment.

"There aren't many choices," said Ms. Bennett, apologizing for the decor -- bulging plastic bags of clothes that serve as a HTC headboard on one child's bed and a broken couch whose innards have been pawed by a sleek black and white cat called Queenie. "We stay here, or we move back to a shelter."

"Having your own is always better, being able to accumulate and settle and be in one place. When you're homeless, people get tired of you. You can't be comfortable no place but in your own house," added Ms. Bennett, a ninth-grade dropout who wandered in and out of homelessness for nearly three years before moving into her apartment two years ago. "There are flaws in the system. If we go back into the system, then the system doesn't work."

In the South Bronx, a half-dozen caseworkers for Homes for the Homeless -- which has moved 1,600 homeless families into permanent housing since 1987 -- advise about 45 families apiece. The great majority of clients are at risk of losing their apartments as a result of substance abuse, domestic violence, child abuse or neglect, medical or maintenance problems or administrative mishaps that have bungled their government rent subsidies.

Advocates will work with a family from three months to a year, depending on the severity of the problems. Sixty-percent of the families have never had apartments. Many aren't receptive: 40 percent don't show up for appointments with their caseworkers.

"In the early days, we'd see families over and over again, the same families coming back into the shelters," said Ralph Nunez, president of Homes for the Homeless, which receives private and government funding, much of which is from the city of New York. "One guy hit all three of our facilities and was placed [in housing] three different times. At least now when we walk [away from a client] we know the chances [of repeat homelessness] have been greatly reduced."

Results are encouraging: The three shelters operated by the agency post a return rate of 6 percent, compared with a rate of 20 to 30 percent for the city-operated shelters, which offer no after-care and provide far fewer shelter services.

"After-care is probably the only tool that will maintain formerly homeless individuals and families in their homes," said Geraldine Hailstolk, who is on the faculty of the School of Social Work at the University of Maryland at Baltimore. "Obviously, if they've been homeless for a while, a number of issues are arising for them. Having a case manager working with a family is really the only way to maintain them. It's certainly the wave of the present, and it's got to be institutionalized."

"Homelessness has become an increasingly difficult issue to manage," said Ms. Hailstolk, who has worked with the homeless in New York and Baltimore. "While a job is absolutely critical, while a house is absolutely critical, you've got to get them to a point where they can go after those things. You can have a thousand houses, but if you don't have even the basics down, I'm not sure how good that house is going to be."

However, some advocates for the homeless are cautious about the use of after-care.

"I don't think anyone would say it's not working," said Tom Kenyon, president of the National Alliance to End Homelessness. "However, we feel often the public sector stays in a person's life too long, causing one to become dependent on that person rather than learn the skills they need to function independently."

And John Belcher, a University of Maryland at Baltimore assistant professor who last year authored "Helping The Homeless," noted: "I don't think it works at all. The problem is joblessness and these programs don't change that. It's just another Band-Aid that adds another layer to what has, in effect, become an industry."

In New York, the Edna McConnell Clark Foundation has funded four community-based agencies that will offer up to 10 hours of services a week for a three-month period to families in danger of falling back into homelessness. The program will serve 200 families this year in Central Harlem and the South Bronx.

"I agree that jobs are the answer. Housing is the answer," said Susan Notkin, the foundation's director of programs for homeless families. "But some families are very fragile. This is designed to limit dependency and help families become empowered. You can't do anything without housing."

In its pilot program in 1989, the foundation offered intensive services to nine families for six weeks. In the two years since, Ms. Notkin said, the families have made some impressive gains. A couple of people have gotten their high school equivalencies. A few of the families have straightened out problems with their rent subsidies. Some of the children, dropouts to start, have gone back to school, and several families have been reunited with children who had been placed in foster care. Ms. Notkin said she knew of only one family that returned to a shelter.

Courtney Foster, a former homeless woman who is an after-care worker for Homes for the Homeless, said: "I remember the first time I saw an after-care folder on the desk. I was the client. I was insulted. Well, I've learned a lot since then. There is so much ignorance. I've met people who've been in the shelter system for two years, five years, seven years.

"A lot of these people didn't have parents to teach them. Now, the doors are beginning to open for them."