Three months ago, Jamir London, 19, was one of Philadelphia's "disconnected" young people, cut off from school, from work, and from hope.

"Didn't have a job. Didn't have no income, doing all the wrong things," London said, as he sat on a stoop outside an abandoned house in Nicetown.

Both the house and London are on the mend now, but it doesn't surprise him to learn what a Drexel professor unearthed in his dive into census and labor-market statistics.

By this professor's count, nearly 43,000, or one in four people in Philadelphia between 18 and 24, are "disconnected" - out of school and out of work.

"Holy cow," said the professor, Paul Harrington, a labor economist at Drexel University's Center for Labor Markets and Policy. "I was pretty surprised when I saw the numbers. It means you've lost a lot of productive potential."

In the region, the loss of "productive potential" numbers nearly 85,000, or 18.5 percent of those 18 to 24 living in Philadelphia and in nearby Pennsylvania and New Jersey counties, Harrington wrote in a report, released this month, titled "The Human Capital Deficit of Disconnected Youth in Philadelphia."

Nationally, there are nearly five million "disconnected" young people, or 17.7 percent of the age group, the report said.

The gist is that young people with less education who haven't worked are less likely to be working at a key time "when kids are making life decisions," about careers, families, marriage, Harrington said.

"It means your future employability prospects are dim. You are on a lousy earnings pathway and a lousy income pathway," he said. "The odds have shifted against you."

Beyond the individual, the aggregate lack of contribution by the group means that society doesn't get the benefit of their human capital, their knowledge, their creativity, and their labor, Harrington said.

London, who embodies both the disconnect and the opportunity, also has an analysis.

"If you have a family and all they know is the street - a lot of people don't have their dads around - and if all the family members are on drugs, it rubs off on you," London explained. "It goes from generation to generation, and we get comfortable with that, even though we know we shouldn't."

London is now grabbing hard to the opportunity part, enrolled since August in YouthBuild Philadelphia Charter School, which admits 200 high school dropouts, aged 18 to 21, who usually aren't working.

Some have been in prison. Some, like London, of West Philadelphia, have teetered on the edge of homelessness. He was kicked out of his family's home at one point, going from sofa to sofa, watching his siblings fall apart in different ways, his mother unable to help.

"All that stress was going on - me not having money, nothing to eat in the house," he said.

Then, with his girlfriend pregnant, he saw an advertisement for YouthBuild on the side of a bus and signed up, choosing its construction program.

On Tuesday, London, in work boots provided by the program and wearing a toolbelt, took a break to talk as his classmates carted construction materials into two abandoned Nicetown homes the students are rehabbing, using materials donated by Saint-Gobain Corp. North America, the building-materials firm in Valley Forge.

"I look at life differently now," London said.

So does Siani Clemonts, 19, of North Philadelphia, who is motivated to improve the life of her 11-month-old daughter. Her hope is to graduate from YouthBuild, go to college, and return to YouthBuild as a "young professional," or an instructor.

"I deserve more than the street," said Clemonts, who attended three high schools before dropping out. "I was tired of the bad stuff. Nobody had nothing good to say about me, but now it's positive."

Harrington says the solution begins well before age 18 with dropout prevention in the schools and a stronger career tech component, particularly for males, at the high school level, forging a stronger link from education to employment.

After that, though, the government should intervene, he said, with a direct employment program - putting young people to work cleaning up, or caring for the elderly, or revitalizing neighborhoods.

"We should have a policy that we don't want 18-to-24-year-olds hanging around. We want them busy," he said. "In some neighborhoods, we need to bring the idea of work back into the neighborhood."

Meanwhile, Harrington points to programs already in place, such as YouthBuild Philadelphia Charter School.

About 70 percent graduate from the school, officials said, and 80 to 90 percent of graduates go on to college or jobs.

Harrington also points to the 100,000 Opportunities Initiative, launched this summer in Chicago, by a group of major employers, among them Walmart, Starbucks, Target, and CVS, which have committed to creating training and career paths for this group of young people.

"These kids have faced tragedy and trauma," said John Ducoff, executive director of Covenant House in Philadelphia, which houses homeless people 18 to 24 who are often jobless as well.

"But the opportunity is adolescence," he said. "These teenagers are still developing, so it's a tremendous opportunity" to put them on the right path.

In Camden, the county's Workforce Investment Board is addressing the issue with an employment agency geared for young people, a variation of the adult One-Stop Career Center funded by the state.

"The challenges the youth face are very different from those adult job-seekers face," said Jeffrey Swartz, executive director of the workforce board.

The young people, he said, often have less stable home situations and very little experience with the fundamentals of employment, such as showing up on time and taking orders from a boss.

"They need some direction," he said, "and a hand to hold."