An unlikely, largely unnoticed change is underway in the Washington area, one of the nation's priciest housing markets: More and more people with modest incomes are buying homes.

Two decades ago, about one in five households in the Washington area with income of less than $35,000 a year owned a home. Now, according to 2000 Census figures, one in three does -- nearly 133,000 households.

Not only is that increase sharper than it is in the rest of the country, it is an unexpected trend in a region where home values have risen dramatically over the past decade. And it is happening in a metropolitan area where a shortage of affordable housing has left tens of thousands of other families struggling to find any place to live.

For decades, broader homeownership has been promoted as a national goal, viewed as helping people build equity and financial security. Advocates argue that it also strengthens neighborhoods by giving people a financial stake in the fate of their communities.

But this rush to sign mortgage papers also carries risks: Census numbers show that most modest-income households spend at least a third of their income on housing costs, more than federal guidelines recommend. That can leave families choosing between mortgage payments and other bills. And as the economy has weakened, foreclosures are rising, many involving lower-income families with thin savings accounts and unstable jobs.

The pool of modest-income owners swelled in the 1990s partly because of the strong economy, which guaranteed nearly everyone a job. Mortgage lenders were pushed to expand their clientele to include more minorities and people with credit problems in their past. And many local governments expanded their programs to help lower-income families buy a home, a considerable task in this affluent region, where the median household income is $64,000.

"There is no one in our country who should be told, 'Homeownership is not for you,' " Mel R. Martinez, U.S. secretary of housing and urban development, said at a national affordable housing conference in Washington last month.

Donna Bah, who was homeless a decade ago, is in this growing group of homeowners. Two years ago, she bought a $114,000 townhouse in Montgomery County, becoming the first homeowner among her five brothers and sisters.

"By the grace of God, it's really panned out," said Bah, 37. "I am in the mainstream. I am with the rest of the folks."

Bah, who makes about $40,000 a year as a licensed practical nurse, said she had to hunt to find an affordable home in a neighborhood in which she felt safe. And she made sacrifices to buy it.

"I learned how to repair my credit, how to budget," she said. "I lived on Oodles of Noodles and tuna fish, not eating out, not buying any clothes."

Even so, she could not quite save enough. To help with closing costs, she received a loan from a Montgomery program.

Now, Bah tries to be tightfisted, making plumbing repairs herself and accumulating enough savings to stay two or three months ahead of her mortgage. She also enjoys the simple pleasures of homeownership, such as planting a "little bitty herb garden" with basil, sage and thyme.

Last year, according to figures collected by the Metropolitan Washington Council of Governments, more than 22,000 home buyers received such assistance in Montgomery, as did more than 8,700 in the District and 1,300 in Fairfax County. At the same time, local officials say that these programs fall far short of addressing the need.

The number was significantly lower in Prince George's County, where just 149 buyers received government help. That is largely because Prince George's has the region's largest stock of affordable housing. The average home in the county sells for about $150,000, which is within the reach of most Washington area families, County Council member Peter A. Shapiro (D-Brentwood) said at a recent regional affordable housing conference.

That also explains why Prince George's has the largest number of modest-income homeowners -- nearly 23,000 -- in the Washington area.

An affordable-home lottery in Montgomery helped Abigail Sawyer, 43, an accounting assistant whose family income is $38,000, buy a $123,000 townhouse in Germantown in August.

"I am paying $50 more than I used to pay for rent. It is not a big adjustment, but it is a much better deal," she said. But, she added, "I have to watch how I spend."

Josette Bailey signed mortgage papers in June on a brick-and-frame townhouse in Southeast Washington that cost about $125,000. That was a remarkable day for Bailey, who was bankrupt three years ago. Now, she earns less than $30,000 as a medical bill collector for a doctor's office in the city.

After her bankruptcy, Bailey was determined to make a comeback. She bought a car and worked on polishing her credit record. "Then I said, 'Let me take this other challenge,' and that was to purchase a home," she said.

Bailey, 34, wanted a home in Northwest, to stay near her job, but prices were too high. So she looked in less-expensive areas of the city. Now, she shares her new home with her fiancee, her 19-year-old daughter and 6-year-old son.

In hot real estate markets such as Washington's, buyers often can build equity quickly.

"This is a way of people participating in housing price increases and growing their wealth," said Susan M. Wachter, a former federal housing official who teaches business at the Wharton School of the University of Pennsylvania.

But the problem of spending an excessive share of income on housing is getting worse, according to Census Bureau figures, and now affects more than half of modest-income homeowners.

Federal guidelines recommend that people spend no more than a third of their gross income on housing costs. In this region, about six in 10 homeowners with annual incomes of less than $35,000 spend more, the 2000 Census shows. That compares with about four in 10 nationally.

An even starker picture emerged from an analysis of a Census Bureau housing survey by Fannie Mae and the Urban Institute, which said many moderate-income homeowners in the Washington area spend more than half of their income on housing. A recent national report by the Center for Housing Policy found similar trends across the country.

"The unsettling reality . . . is that these problems worsened during a period when the economy was doing relatively well," said Jared Bernstein, co-director of research for the Economic Policy Institute.

When an owner is stretched so thin, it takes only one problem to create a crisis.

Harris S. Ammerman, a D.C. bankruptcy lawyer, has a stack of file folders on his desk with the hard-luck stories of modest-income homeowners. There is the couple who split up and fell behind on the mortgage in Southern Maryland. The police officer who accumulated a pile of other debts. The two-income couple who went into delinquency when one of them lost a job. A growing number of his clients are from Prince George's, where he said he has seen an increasing number of foreclosures.

Once it happens, it is almost impossible to turn around if the delinquency goes above $10,000, Ammerman said. Then he tells his clients they will probably lose their home: "I say, 'Where did you live before? You are going to have to go back to it.' "

Sitting on their white tufted velvet couch in the home they have owned in the District for more than 30 years, Doris and Aaron Long are waiting for the ax to fall. They are thousands of dollars behind, and their mortgage holder is about to foreclose on their brick home in Southeast.

They say their troubles began when they refinanced in 1995 and their lender misled them, obligating them to a higher payment than they had agreed to. Then Aaron Long, 67, developed a kidney ailment and had a heart attack. He had to stop driving a taxi, which had supplemented his government pension.

The Longs' income, once $35,000, fell to $25,000. Their monthly mortgage payment of $1,200 eats up more than half of that.

"Your life savings are gone," said Doris Long, 68, who is taking computer classes in hopes of providing some family income. "If I had just known."

Mortgage delinquency is at record levels across the country. In some cases, people have to put up only a few hundred dollars to buy a home and may have nothing in reserve for a crisis.

Increasingly, researchers warn, there is a two-tier mortgage market in which lower-income buyers are more likely to get loans with higher interest rates, sometimes from unscrupulous lenders.

"A lot of the affordable mortgages at this point are really pushing the envelope," said William M. Rohe, director of the Center for Urban and Regional Studies at the University of North Carolina at Chapel Hill. "They are qualifying people who really don't have a high probability of being a successful homeowner."

Academics and advocates also point out that homeownership offers fewer benefits for people of modest incomes -- most, for example, earn too little to be eligible for the mortgage-interest federal tax deduction. They also are more likely to buy in iffy neighborhoods where values may not rise.

"The overall message is that this is a good thing for most people, but there are some important cautions," Rohe said.

That is why Willamena Samuels mixed stern advice with encouragement as she convened a recent monthly meeting of a savings club she directs for would-be home buyers at Manna Inc., a nonprofit housing developer in the District.

Seated around a conference table were 16 women and one man, leaning in to listen as Metro trains rumbled nearby in the night. If they could put aside $800 in two years, they would be eligible for a $4,000 grant to help them buy a house.

Manna's clients have incomes of up to $36,000. Many are single mothers, and often the new ones have no idea what a credit report is. A growing number are immigrants who may not trust banks. Some are remarkably persistent: Two of this year's buyers had worked toward ownership for a decade, increasing their incomes and cleaning up their credit.

Samuels, once a Manna client herself, knows how vulnerable her charges are. She loads them up with warnings: Avoid predatory lenders. Don't sign something without reading it carefully. Don't depend on a romantic partner to be a co-signer, because the partner might walk away later.

"I see women come by, all in love, and they want to buy a house," she told them. "Always make sure that if you fall out of love, that you can handle it."

Database editor Dan Keating contributed to this report.

Josette Bailey and her son, Derrick, relax in their Southeast Washington townhouse, which a determined Bailey was able to buy just three years after she was bankrupt.