The number of minorities in college has increased substantially in recent years, but not fast enough to keep up with demographic changes.

As a result, U.S. adults in their late 20s are reaching only about as far as the age group immediately above them in terms of educational attainment. And among Hispanics, a lower proportion has completed at least an associate’s degree when compared with those age 30 and older.

Unless the trend is reversed, the increases in Hispanic participation in higher education won’t be enough to ensure that a growing proportion earn a college degree.

The findings are highlighted in a biennial report to be released today by the American Council on Education, supported by the GE Foundation.

“One of the core tenets of the American dream is the hope that younger generations, who’ve had greater opportunities for educational advancement than their parents and grandparents, will be better off than the generations before them,” said council President Molly Corbett Broad. “Yet this report shows that aspiration is at serious risk.”

The report does show notable progress for minorities in higher education in several areas.

Between 1995 and 2005, total minority enrollment on U.S. campuses rose 50 percent, to 5 million students. The numbers of Hispanics receiving bachelor’s degrees has nearly doubled over that period, as has the number earning doctorates.

However, significant gaps among racial groups remain, and by some measures are widening. In 2006, among 18- to 24-year-olds, 61 percent of Asian-Americans were in college. That compares with 44 percent of whites, 32 percent of blacks and 25 percent of Hispanics.

Department of Education figures show that in 2006, 18 percent of older Hispanics had at least an associate’s degree, compared with just 16 percent of 25- to 29-year-olds. Council researcher Mikyung Ryu said the numbers do not suggest that’s simply because students are delaying getting an associate’s degree until after 30.

“The fact that this younger generation is attaining less than the older generation should really be ringing bells across this nation, and we really should be asking ourselves why,” said Dolores Fernandez, president of Eugenio Maria de Hostos Community College, which is part of the City University of New York.

The report also highlights a growing gender gap. It says, 36 percent of young men were enrolled in college in 2006, compared with 44 percent of young women.