DURHAM, N.C. — Duke University on Saturday became the latest elite college to announce a major boost in financial aid. But like even some of its wealthiest peers, it isn’t going so far as to guarantee all its students will graduate debt-free.

Instead, Duke — which has a list price of more than $45,000 per year — said it would stop requiring any parental contributions from families earning under $60,000. Students from families earning less than $40,000 will get a full ride, without being asked to take out any loans.

But while better-off students won’t have to borrow as much as before, Duke will still ask them to take out some loans. That differs from new policies announced by a handful of prominent colleges recently, including Princeton, Davidson, Amherst and Williams — all of which have replaced loans entirely with grants that don’t have to be repaid.

Duke says even with a $5.9 billion endowment, it doesn’t have as much to spend per student on financial aid as the schools that have eliminated loans. But even some schools with much bigger endowments than Duke, including Harvard, Yale and Stanford, still ask students to borrow. They argue a degree from an elite school is worth so much over a graduate’s lifetime that a small loan is a reasonable investment to require.

“In my judgment it is not inappropriate to students to consider helping support their cost of attendance,” said Duke financial aid director Jim Belvin. “What we want to do is lower that burden on students.”

Duke officials say that as they debated how to cut Duke’s expanding financial aid pie, they decided to lower the maximum students have to borrow, but to channel much of the break to parents, since it’s students who benefit most directly from the degree.

“We’ve done away with the parental contribution for what amounts to half the population, the bottom half of median income in America,” Duke President Richard Brodhead said in a telephone interview.

Duke’s announcement is the latest in a string by prominent schools which, even as their list prices skyrocket, are competing to offer better and better deals to low-income students. As a group, elite campuses have faced criticism for their lack of economic diversity.