Higher-education officials are right when they inevitably point out that inequalities in student performance stem from socioeconomic inequities in society and the failure of our elementary and secondary schools to remedy them. Less acknowledged: Instead of counteracting the inequalities they inherit, colleges and universities magnify them.

Higher education in the United States is highly stratified, showering the most resources on the most-advantaged students. Low-income and minority students are concentrated in community colleges, which spent an average of $12,957 per full-time-equivalent student in 2009, while higher-income and white students are disproportionately educated at private four-year research institutions, which spent an average of $66,744 per student.

Our system of college admissions exacerbates inequalities. Colleges pride themselves on defending race-based affirmative-action programs, but their policies tend to benefit the most economically advantaged students of color. Most colleges do little to provide affirmative action for low-income students, despite rhetoric to the contrary. Research published by the Century Foundation has found that while affirmative action triples the percentage of black and Latino students compared with the share who would be admitted based on grades and test scores, the lower socioeconomic half of applicants receives no break in admissions. Meanwhile, legacy preferences for the children of alumni increase one's chance of admissions by 45 percentage points, aiding an already highly privileged group.

Similarly, colleges have tilted away from economic need to merit aid. At the same time, the federal government gives tax breaks to wealthy students. Less than one-third of the American population has bachelor's degrees—the rationale for using public money to support a fairly small group at the top is that we all benefit when more students are educated. The corollary is that we should focus aid on those students who would not attend and complete college but for public aid—a notion we've lost sight of when we subsidize those who would attend anyway.

Higher education could reduce inequality by eliminating tax breaks for non-needy students and increasing need-based aid; by providing better financing of community colleges and allowing them to offer bachelor's degrees, which would attract more of an economic mix (something, new research suggests, that improves the performance of low-income students); and by employing class-based affirmative action and eliminating legacy preferences in elite-college admissions.

Timothy Noah's new book, The Great Divergence, notes that in the United States today, "parentage is a greater determinant of a man's future earnings than it is of his height and weight." Steps such as the ones I've outlined would move us toward a fairer society in which children of short parents might still grow up to be short, but children of low-income parents would be less likely to end up poor adults.

Richard D. Kahlenberg is a senior fellow at the Century Foundation.