Other private schools around the country have moved to promote racial, ethnic and income diversity by reducing the price of college. The free-tuition movement has been concentrated at opposite ends of the educational spectrum, in community colleges in cities like Chicago and states like Tennessee, as well as in the most elite schools.

Both Harvard and Stanford make tuition free or close to it for students from families with incomes of up to $150,000, nearly twice the threshold set by U.S.C.

States have also sought to reduce costs at their public colleges, with nearly half, including New York, Oregon and Tennessee, guaranteeing free tuition at two- or four-year schools to their lowest-income residents. New Mexico lawmakers are debating a plan to make tuition at the state’s public colleges and universities free for all residents. And the University of North Carolina at Chapel Hill, where Dr. Folt was chancellor until recently, has steadily increased its percentage of low-income students.

U.S.C.’s plan takes a page out of the University of California’s playbook, setting the same family income limit for tuition-free education — $80,000 — as the public system’s “Blue and Gold Opportunity Plan.” U.S.C. said it will increase the amount of undergraduate aid it offers by more than $30 million a year, mainly through philanthropy, giving more help to 4,000 students a year.

About a third of the fall 2020 and spring 2021 entering classes will benefit either from free tuition or larger aid packages, the school said. “This will be a focus of our fund-raising efforts going forward,” said Eric Abelev, a school spokesman. Its last campaign raised $7 billion, including $636 million for scholarship support.

Currently, 31 percent of U.S.C.’s undergraduate students come from families in the bottom 60 percent of income earners nationwide, the school said. The student body, including graduate and undergraduate students, is 29 percent white, 5.3 percent African-American, 16.9 percent Asian-American, and 14.6 percent Hispanic, with 25.4 percent from other countries.

“It’s fitting that U.S.C., which was at the center of the Varsity Blues scandal, would take this important step,” said Richard D. Kahlenberg, a senior fellow at the Century Foundation who studies college opportunity for low-income students.