Princeton University did something this year it hasn’t done since 1990: It accepted transfer students. (Associated Press)

In May, Princeton University announced that it accepted 13 transfer students for this fall’s freshman class. And while that is a tiny fraction of the 1,300 students expected to arrive this fall on campus, the news was still significant: It marked the first time since 1990 that Princeton had accepted transfer students.

The image of the modern undergraduate is no longer one that packs up the family minivan three months after high school graduation to move away to college for four years. More than one-third of college students today transfer at least once before earning a bachelor’s degree.

Many come from community colleges, where some 40 percent of all undergraduates begin their journey in higher education. But there’s a problem: While 80 percent of community college students say they intend to transfer to a four-year school, only 14 percent in recent years earned a bachelor’s degree within six years of starting at a two-year college. And while some students who fail to transfer may end up earning an associate degree, that two-year diploma is often in a general field designed to lead to a four-year college. As a result, the degree offers graduates little advantage in a competitive job market that values specific skills.

Much of the blame for the low transfer rate from community colleges is placed on students. The conventional wisdom is that they started at community colleges because they couldn’t succeed at a four-year school. But new research shows that even students who earn top grades at two-year colleges fail to move on. An analysis from the Aspen Institute College Excellence Program found that more than 50,000 community-college students every year who are prepared for a four-year college don’t enroll. About 15,000 of these students earned at least a 3.7 grade-point average at a community college. Many of these students are minority and low-income.

Josh Wyner, executive director of the Aspen program, describes these students as a missed opportunity for four-year colleges. “There are so many talented students in our nation’s community colleges,” Wyner said. “For many of them, completing a bachelor’s degree from a top four-year institution will expand their chances of success.”

But any suggestion that top colleges take more transfer students — or any at all — has often been met with opposition on many of these campuses. Selective colleges — those that accept fewer than 50 percent of applicants — are already inundated with applications from traditional high school seniors. Although they enroll only 20 percent of the nation’s 17.5 million undergraduates, these institutions account for more than one-third of college applications.

But the attitudes of top institutions toward transfer students are beginning to change. Why? It’s the growing perception that their campuses have become havens for wealthy (and usually white) students even as the nation grows more diverse racially and economically.

About one-quarter of the richest students attend a selective, elite college, according to a 2017 study that was the most comprehensive ever on the economic diversity of college students. By comparison, fewer than one-half of 1 percent of children from the bottom fifth of U.S. families by income attend an elite college.

Transfer students offer one approach for top colleges to diversify their enrollment without altering competitive admissions policies for high school seniors or significantly expanding the size of their first-year classes. Even small fixes to transfer policies like the one Princeton recently enacted hold promise.

Consider the 290 institutions eligible for the American Talent Initiative, an alliance of colleges that includes all of the Ivy League schools. All of the initiative schools graduate more than 70 percent of their students in six years. Across these institutions, only 18 percent of new students are transfers, compared with 32 percent at all four-year institutions. The American Talent Initiative has committed to enrolling and graduating 50,000 more low-income students by 2025. If all the schools eligible for the alliance enrolled just 40 transfer students a year, the group estimates, it would be nearly halfway toward its goal.

But persuading these schools to take more transfer students will take more than public shaming. Transfer students often don’t have advocates or receive the advice high school counselors provide to seniors. They usually don’t have the legacy status of their parents like some applicants coming out of high school. And transfer students don’t count in the college rankings.

Elite schools need incentives to build the pipeline to enroll more transfer students. Those incentives could come from the federal government, perhaps through a break on the new endowment tax that is part of the larger tax bill signed by President Trump in December. They could come from community colleges that need to do more to identify and promote their high-achieving students. And it will come from efforts such as the American Talent Initiative that encourage colleges to improve by cooperating with one another.

Community colleges represent an affordable pathway to a college education for millions of students each year. Those students shouldn’t be derailed in their pursuit of a four-year degree because top colleges think they’re not cut out for their campuses.