Pennsylvania significantly trails many states in the percentage of working-age adults enrolled in college, a statistic that is slipping both here and nationally, a report being released today says.

The decline among those 25 to 49 years old is one of the concerns outlined in the National Center for Public Policy and Higher Education's latest state-by-state report card on higher education.

In its wide-ranging study, the center points to noticeable gains nationally in college preparation and access, especially for 18- to 24-year-olds. But the authors of "Measuring Up 2008" also say race and income remain barriers to college opportunity, and that the United States is losing ground to education systems in other countries.

Only 39 percent of young adults in America have at least an associate degree, a percentage that now trails nine other countries, the study noted. Those working on a degree shoulder more than twice as much debt as a decade ago because tuition and fee increases are outpacing gains in financial aid.

The center, which gives letter grades to states for college preparation, participation, affordability, completion, learning and benefits from education, said gains made in this country pale compared with the magnitude of the challenges.

The study's authors say that does not bode well for a country trying to compete amid a major economic downturn.

"We're losing our international leadership," said Patrick M. Callan, president of the independent nonpartisan center based in San Jose, Calif. "We have made only modest progress, and in affordability, the whole country has gone south. I think we gave 49 states an F."

Only California received a passing grade in affordability, a C-minus.

In some respects, the nation's educational strength is invested "in a group that's ready to retire," Mr. Callan said. It shows in the declining share of working-age adults pursuing a degree or other college-level training.

Nationwide, the percentage of those 25 to 49 who are enrolled, relative to the total in that age group without bachelor's degrees, slipped from 7.2 percent nationally in 1991 to 5.7 percent in 2007, the study found.

Pennsylvania's share was about half that of top performing states, slipping from 5.8 percent to 3.8 percent, or about four out of every 100 people.

While cost can be a barrier to higher education, the center hasn't taken a close look at why that specific demographic has declined. In a briefing prior to the study's release, officials said reasons for Pennsylvania's low rank may include financial aid policies unfavorable to those trying to enroll part time.

Among 18- to 24-year-olds, the picture in Pennsylvania was brighter. The share enrolled in that age group rose from 30 percent in 1991 to 38 percent in 2007, higher than the national rate.

Overall, Pennsylvania received a C-minus for college participation.

The center gave the state a B-minus for college preparation. The report's authors said eighth-graders "perform very well in math and reading, but their scores in writing are only fair."

Pennsylvania scored an A for college completion. Sixty-five percent of college students finish a bachelor's degree within six years, making the state a top performer, though just 47 percent of black students finish in six years compared with 66 percent of white students.

Even with financial aid, poor and working class families in this state must use 61 percent of their income to pay costs at public four-year colleges. That fact contributed to the state's F grade in affordability.

In the area of benefits from college, Pennsylvania received a C. The report said the state would have $11 billion more in personal income if racial and ethnic groups had the same degree attainment rate and income as whites. Fifteen percent of blacks have a bachelor's degree, compared with 30 percent of whites.

Nationwide, the share of high school freshmen in college by age 19 rose from 39 percent to 42 percent. But Mr. Callan said too many students are unprepared and in need of remedial help.

Like all other states, Pennsylvania received an incomplete in learning because there is not sufficient data to allow meaningful state-by-state comparisons.

Some of the study's most pointed observations involved cost. Mr. Callan said a 439 percent surge in tuition and fees between 1982 and 2006 outpaced a 251 percent increase during the same period in medical care, a 147 percent rise in median family income and a 106 percent rise in the consumer price index.

Placing the brunt of college costs on families, he said, becomes self-defeating for some students.

"If they don't believe they can afford college, they have no incentive to stay in high school, or to take a tough curriculum," he said.