A former high school basketball star, Mr. Bailey said he had to turn down several college scholarships when he graduated so he could find a job and support his mother, who was ill, along with his younger brother. Later, he enrolled several times in various college programs, but the demands of being the family’s primary breadwinner left too few hours for schoolwork.

The biotech training program was to be a way to jump ahead, putting him in position to earn $17 to $18 an hour, as well as health benefits, as a warehouse or maintenance worker in an industry that offered other chances for advancement. But despite applying for about 100 jobs over the last six months, he says, he has never been invited to an interview.

Last summer, a month after the course ended, he went to a job center in East Oakland and was surprised to bump into six of his classmates.

“I was like, ‘Oh man, you’re all here too?’ ” Mr. Bailey said. “We all started looking at anything at that point. It was kind of depressing.”

RECENTLY, he began applying for the same types of jobs from which he had hoped to escape. Now, even those jobs seem beyond reach. He did take one warehouse job that started at 5 a.m. and required him to walk two miles to and from work, but he quit in disgust after two weeks. It paid $10 an hour  two-thirds of what he used to make as a truck driver.

He applied for a minimum-wage job at Wal-Mart, but after two interviews the person doing the hiring was fired, he said, and Mr. Bailey was told that he had to start all over  this for a night shift at a store in an area plagued by crime. Disenchanted, he stopped pursuing a career at Wal-Mart.

“I’ll just look for anything now; it doesn’t matter,” he confided on a recent afternoon.

The next day, he accepted a job at a warehouse for $9 an hour.

“It’s just picking up boxes,” he says. “That’s all right. I’ve got to do something.”