COLLEGE TUITION COSTS keep rising at rates far faster than families' incomes. The increases have been unusually large at the colleges and universities in the Washington area. The institutions seem collectively to have become fashionable, a condition of mixed rewards but one that has allowed many of them to push up costs much more rapidly than the national average. As Lawrence Feinberg reported in this newspaper, at most of them the tuition and fees next fall will be 50 percent to 100 percent higher than five years earlier. The inflation rate over those five years will have been less than 25 percent.

That is reason for real concern. In those same five years, student aid from all sources -- the federal and state governments, and the colleges themselves -- has risen no faster than inflation. Worse, federal aid to students is now offered mainly in the form of loans. Even if these loans were endlessly available, there are clear limits to the amounts of debt that ought to be loaded onto young students pursuing bachelor's degrees.

What's driving the steady escalation of college costs? The colleges with the highest reputations have discovered that tuition increases seem to have no effect on the flood of applications to them. That makes it difficult to resist the inclination to keep raising faculty salaries, adding other improvements in the quality of education and lifting students' standard of living as well. College food tends to be a great deal better these days than it was a decade ago -- let alone a generation ago. As the best-endowed colleges make these pleasant changes, the others struggle to keep up. Sometimes, despite their misgivings, colleges raise their tuitions out of anxiety that applicants will take a low price tag to mean low quality.

Inevitably this self-perpetuating process of annual increases limits the opportunity for many capable youngsters to go to college. Is it necessarily foolish for young people, uncertain about their futures, to hesitate to assume debts of many thousands of dollars? These financial pressures seem clearly to contribute to the falling proportion of black students who, finishing high school, choose to go on to higher education.

Over the past generation, colleges and universities have been the most powerful of all the forces diminishing the distances among the social and economic classes in American society. It would be tragic if, in their rising prosperity, they were instead to allow themselves in the next generation to reinforce those distinctions. To break the present pattern of large annual increases in costs will require the exercise of great restraint, and the leaders will have to be those institutions of highest standing and greatest wealth. Otherwise all of the colleges and universities together will keep racing up a road that each of them correctly deplores.