Attending a community college appears to substantially improve a welfare recipient's earning potential, according to a new study of low-income Californians.

The study, released on Thursday, was sponsored by the chancellor's office of the California Community Colleges system and by the Center for Law and Social Policy, a nonprofit organization that advocates on behalf of low-income families.

The researchers tracked female welfare recipients who left one of California's public community colleges, with or without a degree, during the 1999-2000 academic year. The study examined the women's employment rates and median earnings over time.

The study found that, two years after earning an associate degree, welfare recipients were earning about five times what they had earned before entering college. Their median incomes rose to $19,690 from $3,916.

Welfare recipients who earned a vocational certificate were making more than three times as much money two years after leaving a community college as they were earning before enrolling. And the longer the vocational program, the study found, the greater the economic payoff. Generally, students needed to earn at least 30 credits in vocational programs to be making more than $15,000 two years after receiving their certificates.

A report on the study's findings challenges the argument that attending a community college distracts a welfare recipient from finding work. It notes that 56 percent of the welfare recipients who attended a community college were working during their last quarter of classes, while just 44 percent of the overall welfare population was employed at that time.

The researchers caution that their findings are slightly skewed by differences in the educational attainment and aspirations of the various populations of welfare recipients that they studied. For example, 62 percent of those who had chosen to attend a community college had a high-school diploma, compared with 49 percent of all welfare recipients.

The researchers sought to account for such differences by conducting a separate analysis examining only those welfare recipients who had enrolled at a community college without first earning a high-school diploma. The scholars found that a community-college education made nearly as big a difference for that population as it did for welfare recipients who were high-school graduates.

"This study shows that allowing welfare participants access to postsecondary education is a shrewd, long-term investment," said the report's lead author, Anita Mathur, a doctoral student in sociology at the University of California at Berkeley.