The descent from working class to homeless was swift and methodical. Rob Messick lost his job as a contract worker for a technology firm in Alexandria in September. The bills, already high, piled higher: rent, child support, car insurance, medical expenses, utilities. The odd jobs he scored didn't keep pace. The eviction notice arrived in November.

A few miles away and three weeks later, Messick's girlfriend, Toni Willingham, soon to be the mother of one of his children, also found herself jobless. Her position at a government contracting firm ended. Then she lost the $200-a-month room she was renting.

The young couple found themselves at the Lord of Life Lutheran Church off Braddock Road, where they and several dozen others sought shelter against the cold and the wind and vagaries of lives gone awry in the heart of Fairfax County, the country's second-wealthiest jurisdiction.

"I guess this is going to sound typical, but we really didn't know what hit us," Willingham, 26, said. "Six months ago, you're living a normal life, on your own. Then you make a wrong turn or things get too much, and you're where you thought you'd never be."

Messick, 25, and Willingham, 26, represent a growing underside of the vibrant, rapidly shifting economy of Northern Virginia, where the high cost of housing and the unpredictable nature of the job market can plunge workers into poverty and homelessness.

Although Northern Virginia has one of the lowest unemployment rates in the country, tens of thousands of its jobs are contract work, where moderate income employees such as Messick and Willingham are at the mercy of employment that can end suddenly and disappear forever. Often, workers are able to jump to new jobs without disrupting their lives -- Messick did it for six years. Other times, finding work can be elusive.

"These jobs are becoming a growing share" of the region's economy, said Stephen Fuller, a professor of public policy at George Mason University, who estimates that 200,000 federal contract workers are employed in Northern Virginia and thousands more in the private sector. "Particularly at the low end, [people] work only as long as it's available."

At the same time, the region's high-powered economy has increased housing prices so much that many moderate income workers are not able to keep up. In Northern Virginia, the average monthly rent for a two-bedroom apartment is $1,286, according to a recent report by the National Low Income Housing Coalition.

To afford that level of rent and utilities, without paying more than the federally recommended ratio of 30 percent of income on housing, a household must have an income of $51,440 a year. Messick, who received about $32,000 between his day job and odd jobs, was putting nearly 60 percent of his income into housing.

The situation in Northern Virginia is similar to those surfacing nationwide. Recent research by national poverty experts found that a higher percentage of Americans dropped below the poverty line for at least a year in the 1990s than in the previous two decades -- and they estimate the trend has continued for the past six years.

Large contributors to this temporary "acute poverty" were the rising cost of housing, the volatility of contract work and increasing health care costs, said Mark Rank, a professor of social work at Washington University in St. Louis, who co-authored a 2004 study.

About 3,000 people were counted homeless in Northern Virginia last year, and, like the more than 16,000 across the Washington region, many were drifters and drug addicts. But unlike elsewhere, many homeless in Northern Virginia are members of working families who cannot keep up with rising costs. In each of the area's largest jurisdictions, the majority fit that description.

"These are truly people who are stretched too far," said Pat Johanson, homeless services coordinator for Prince William County, where 75 percent of the homeless are members of families. "They wind up in cars or on the couch of a relative or friends."

That is where Messick and Willingham wound up. For a month, they slept on couches and floors at friends' apartments. Then they slept in Messick's car, in Wal-Mart and in drugstore parking lots. But as temperatures plummeted early last month, they gave into reality and checked into an emergency overnight shelter.

Now the Fairfax County high school graduates spend their days trying to land jobs, without a home, a phone or other basic resources.

A recent -- and typical -- day: Messick's black Hyundai was nearly out of gas. Neither he nor Willingham had any money, and he wanted to get to a job fair 10 miles away. He needed to get a voucher for free gas from a local nonprofit group. He considered skipping the fair because there was a chance that he could get a day job. But first he had to get that free gas.

"They told us to call back in an hour," Willingham said. "An hour? It'll be too late to get up to the [Fairfax] government building by then," he said, tossing a pen in the air.

He never made it, and he never received the call about the day job.

Messick and Willingham, who share matching midnight-blue lion-head tattoos on their arms, have been together for about 10 months. They lived with each other on and off before Messick's eviction notice came, helping take care of children from other relationships, lending each other money, preparing for their baby. Messick's mother is long dead, and he hardly knew his father. Willingham's mother is also dead, and she is estranged from her family.

Still, life was pretty good then. On a typical day, Messick rose at 6 a.m. and took his son to day care. He arrived at work by 8 a.m., stayed until 5 p.m. and then picked up his son. As he describes it, money was tight, but he had enough to live.

"The only problem I had was whether the guy at the deli was going to get my sandwich right," he said.

Willingham worked as a specialist analyzing government contracts, making about $1,200 a month, while holding down a part-time job for $7.50 an hour. There was child care to pay for and all the other necessities. As her pregnancy advanced, finding a new job became more difficult because her health worsened. She lost the baby in December.

"It's like a sideways spiral," she said. "One day is good. . . . You get a voucher for gas, and you get a job interview. Then something happens. You miss a phone call from an employer, and you lose a job contact. You hear about a job, and it doesn't come through and you've lost a morning trying to find another job."

Unlike in the District, where homelessness has been a problem for decades, it is largely invisible to the daily rhythms of life in the suburbs. As a result, suburban counties have struggled to help those on the margins, many who are unaware of the patchwork of assistance available. The wide suburban distances and lack of transportation options complicate matters.

Many communities are trying to do something. Arlington County, Alexandria and Fairfax have plans to increase affordable housing and services to "end homelessness" by the middle of the next decade. Many offer eviction prevention programs and other services.

Nonetheless, nearly every major jurisdiction has a waiting list for family shelter beds. Advocates in Fairfax estimate that, on any given night, dozens of families are on waiting lists for shelters where they can stay for extended stretches. Among Arlington, Prince William and Loudoun counties, nearly 3,000 people were turned away from temporary shelters last year.

Recent zoning battles in nearly every Northern Virginia locality have also slowed efforts to expand services this year, complicating attempts to serve the growing needs during the harsh winter months.

The availability of shelters in the Maryland suburbs, where most homeless people are single, is mixed. In Montgomery County, officials said they have been able to house all of the families and single adults who have come looking for help; in Howard County, waiting lists have grown to as many as 200 people.

Advocates for the homeless said Messick and Willingham's experience illustrates cracks in the system: There are generally no specific shelter services for childless couples. Willingham was told several times that she could get on a list for a guaranteed place to stay for several months if she had her 2-year-old son, who is living with his father, with her.

"There are lots of these couples out here, and this is one of the populations that easily slip through the cracks," said Pam Michell, executive director of New Hope Housing Services in Fairfax.

Bumping from shelter to shelter started to wear on Messick and Willingham by the middle of this month, but day jobs were popping up. Messick started a job scheduled for three days a week, and Willingham was getting bites on work at a hospital. They hoped they would find a home by summer.

"All these years, I looked at people walking around here, and I never knew what they were doing," Messick said one evening after dinner at the emergency shelter. "They were homeless, and I never knew it. Now I am that guy."

But he sounded hopeful: "People tell us, because we're trying hard, it won't take us long. We're both able-bodied. So I believe them."

He unrolled his sleeping bag. The church was about to show a movie, and then it was lights out.