The slumping economy is pushing more and more people in the Washington area into home-sharing as they try to stretch their dollars in the area's expensive housing market.

Applications to Alexandria's Operation Match program, which helps would-be renters find rooms in family homes, have doubled since last year, and the District's matching service now receives more than 50 calls a day, program coordinators said.

Coordinators for the nine metropolitan area matching programs estimate they received 3,500 applications this year, and said they believe that number barely scratches the surface of home-sharers because the vast majority of landlords and tenants find each other through word of mouth or newspaper ads.

Millie, who asked that her last name not be used to protect her privacy, said she decided to rent out the bottom floor of her Reston town house earlier this year when she divorced because, she said, "I could not make enough money to hold onto the house."

Fairfax's matching program sent her a 33-year-old lawyer named Mike who is waiting to pass the Virginia Bar exam. "I'm in a state of flux right now. Until I get settled, I didn't want to be saddled with a long-term lease," he said.

While students and young people just out of college have commonly lived in group houses for convenience and price, Millie and Mike are part of a growing number of older, more established adults who have been prompted by economic circumstances to turn to home-sharing.

Shared housing is on the upswing nationwide, because rising housing prices, and more recently the slumping economy, have made alternative housing attractive. The number of matching groups nationwide has risen from 80 in 1981 to 400 now, said Sam Rhoads, of the Shared Housing Resource Center in Philadelphia.

Thousands of house-poor suburbanites, many of them divorced or widowed parents, are trying to turn their major asset into regular cash to supplement their income and afford burdensome mortgage payments.

"We've had a tremendous influx of providers . . . . So many people in Gaithersburg and Germantown tell us that in order to keep their house, they need a tenant," said Diane Lipskind, who runs Montgomery County's 12-year-old matching program. Montgomery gets far more would-be landlords than it can match with tenants, she said.

For their part, struggling single parents, young professionals and people seeking to move out of homeless shelters are opting for room rentals.

Most can't find an apartment they can afford or don't want to share a group house with several other people, according to the coordinators of the matching programs. The Metropolitan Washington Council of Governments has labeled the shortage of affordable housing one of the region's top problems.

"I spent all my money trying to get an education," said Mike Krivka, 28, who this weekend is moving into a room in a North Potomac house. "I could get a place of my own, but I would be so financially burdened it wouldn't be feasible."

Monthly rent for a room varies widely across the metropolitan area, from $200 to $250 in the outer suburbs to nearly $400 in areas closer to Washington. Efficiency apartments often run $200 higher in comparable areas.

Shared housing is not a new idea. The region's more urban areas used to be dotted with rooming houses.

"At the turn of the century, {home-sharing} was very popular with immigrants and people who were moving into the cities," Rhoads said.

Now, local zoning laws limit house-sharing by prohibiting more than three, or four in some jurisdictions, unrelated adults from living in the same dwelling without a special-use permit or state license. Alexandria officials said they have had to crack down on informal, and illegal, rooming houses that spring up in small Del Ray town houses.

Some home-sharing arrangements are based on services rather than rent. The Miller family in Burke and Angela Pearson agreed to trade room and board for four hours a day of child care and cooking.

"I thought about being a nanny, but this way I can make more money," said Pearson, 20, who works at a day-care center during the day and at a gas station on weekends. "We've become so close that it's like a huge family."

But such arrangements are the exception rather than the rule, because most landlords need the money.

Despite its financial benefits, home-sharing has pitfalls, both homeowners and their tenants said. The arrangements often are very short-lived, with tenants staying for only a few months, or at most a year. Krivka, for example, has lived in five houses in the past six years.

"Every time somebody goes, I feel like I'm losing a friend," said his landlord, Laura Huff, who has seen five people pass through her upstairs bedroom since 1987.

More serious problems also arise. Laurence Reid said he had some trouble when he rented out the three bedrooms on the top floor of his District row house to college-aged men.

"The college types would smuggle another person in {to stay} and pretend they were just visiting," Reid said. "The primary concern with me is drugs."

Reid, like many other landlords, turned to the government matching programs for help in screening tenants. Every jurisdiction in the metropolitan area, except Howard and Anne Arundel counties, has offered the free matching service for nearly a decade.

The program workers discuss issues like smoking, pets and cleanliness with both tenants and landlords. They also check references and, for the tenants, proof of income.

"It was my first experience with sharing a home . . . . Just to do it with a blind ad was frightening." Millie said. "The program removed a lot of strain."

For Pat, a divorced Herndon woman who began renting out a room in her town house after her two children left for college, the $350 a month is vital, but so is "the feeling that if you called out in the middle of the night, someone would be there."