Wealthy universities, under pressure to spend more of their endowments and slow the upward course of tuition and fees, are shifting more of their resources to financial aid, a move that will help more middle-class families afford college. It is also a move that is likely to trickle down to schools with fewer financial resources.

Earlier this month Yale University, the country’s second-richest university, became the second school to announce it would increase the amount it spends from its endowment. Harvard University had already said it was boosting spending from its endowment from a current 4.3 percent to 5 percent. Charles Grassley, the ranking Republican on the Senate Finance Committee, praised both universities for “making tuition more affordable.” Sen. Grassley wants to see a minimum spending limit for universities similar to the 5 percent required of foundations. Voluntary action is better than a one-size-fits-all mandate from Congress.

It’s true that some of the biggest universities are very rich, benefiting from generous gifts and bequests and lucrative investments. Yale’s endowment has doubled since 2003 to $22.5 billion. Harvard’s has reached $34.6 billion.

And it’s also true that the costs of advanced education have risen considerably faster than inflation. A year costs $45,000 at Yale and $45,620 at Harvard.

But these costs, high as they may seem, are often cut by financial aid from federal, state and private sources, and increasingly from the institutions themselves.

Yale charges nothing when families make $5,000 or less a year. Harvard has drastically reduced costs to middle-class and upper-middle-class families with incomes up to $180,000 a year; they will pay no more than 10 percent of their incomes, with the percentage going down to zero for those with incomes at $60,000 or below.

The Princeton Review, an educational testing and support service, reports that the percentage of students receiving needs-based aid is 38 percent at Bates College, 43 percent at Bowdoin College and 37 percent at Colby College. For freshmen the average needs-based gift aid runs from $26,000 to $28,000.

Bates is spending 4.3 percent of its endowment this year and is not planning a change. Colby’s spending has gone up from 4 percent to 4.5 percent but has dropped to 3.7 percent because of good endowment growth. It plans no change. Bowdoin’s spending varies from 4 percent to 5.5 percent and now is at 5 percent.

Last week Bowdoin announced that it would eliminate loans for new and current students receiving financial aid. Current first-year students had been expected to graduate with an average loan obligation of $21,000, which dissuades some students from attending the college altogether and drives the career paths of some graduates.

“With significant debt at graduation, some students will undoubtedly be forced to make career or education choices not on the basis of their talents, interests, and promise in a particular field, but rather on their capacity to repay student loans. As an institution devoted to the common good, Bowdoin must consider the fairness of such a result,” President Barry Mills wrote in a letter to alumni.

If other colleges and universities follow these leads, higher education can become much more affordable.