Aniah McAllister was a lost girl of New York, one of tens of thousands of children edging toward an adulthood drained of hope.

At 18, she possessed just 17 high school credits; she knew the streets and little more. She wandered, almost on a whim, into Bushwick Community High School in Brooklyn, a last-chance school for last-chance kids.

Two years later?

“I’m 20 years old, I have 46 credits, and I want to go to college.”

Ms. McAllister shakes her head, as if amazed to have just claimed that desire as her own. “This school made realize,” she says, “that I am much better than I thought I was.”

That’s a pretty fair bottom line for any school, although in the up-is-down world of public education in New York, it might just be an epitaph for this small marvel of a high school. Known as a transfer high school, Bushwick Community admits only those teenagers who have failed elsewhere. Most students enter at age 17 or 18, and most have fewer than 10 credits.