The new mandate: First, find them a home

"We have no way of knowing beforehand who will succeed and who will fail," said Kathleen Lewis, communications director for SafeHome. She added that the only criterion for helping families is whether they have an ability to pay rent either from jobs or government support.

The SafeHome project is one of only three Housing First programs for families. The others - one run by Episcopal Community Services, another just launched by the city - are also small-scale projects, aimed at rapidly placing families who arrive at shelters into new housing.

Compared with some cities, Philadelphia has been slow to adopt a Housing First approach for keeping families out of shelters. Chicago, for instance, revamped its homeless system in 2003 and has seen shelter capacity drop to 84 percent.

With substantial state help, Chicago will spend $10 million a year to underwrite rents for homeless families and make one-time emergency housing grants. It also will add more than 2,000 units of housing for homeless families.

Philadelphia gets no such support from state government.

The city's program, started last fall, is a $1.6 million pilot to divert families into housing within 48 hours of their showing up at the city's main intake center for homeless families.

The program will find housing for 75 families this year, offering them one-year subsidies of as much as $800 a month. Caseworkers, too, will help with things such as improving credit histories, career counseling, and job placement.

Penn's Culhane, who will evaluate the progress of families and reasons for their success or failure, said Philadelphia now spends about $2,500 a month to shelter a family - money that could go toward grants, relocation funds, or small housing subsidies to get people through housing emergencies.

"Putting people in housing," said Phil Lord, who is running the city's pilot program, "is cheaper than putting them in shelters."

Dainette Mintz, the city's director of homeless services, said Housing First can work for families whose foremost problems are financial. But, she added, those people are not the majority.

Too often, she said, a family is dealing with myriad issues - domestic abuse, addiction, mental illness.

"That is not a family who ideally would be placed in independent housing, where we just start paying their rent and say bye-bye," Mintz said.

Mintz said Housing First was worth developing further, but she is not about to stop funding shelters.

"I cannot flip a switch and move everyone from shelter into housing overnight," Mintz said. "We're going to still have to be funding two systems simultaneously."

Tomorrow: New York City's approach