As college costs rise and student success rates stagnate, states and institutions of higher education have grappled with creative ways to improve student outcomes – particularly for those who are traditionally underserved. Recently, policymakers have increasingly turned to programs that target students even before they enroll full time in college, by implementing and expanding dual enrollment options that allow students to earn college credit while in high school.

In theory, dual enrollment programs (along with programs like Advanced Placement and International Baccalaureate) benefit students in at least two crucial ways. First, by getting college credits out of the way inexpensively (and often for free), students enter college needing to earn fewer credits in order to graduate on time. Second, the exposure to more difficult coursework in a postsecondary-type setting may better prepare students mentally for the rigors of college-level coursework. These benefits may be particularly rewarding for low-income students, who finish college at significantly lower rates than their higher-income counterparts.

These ideas are buttressed by findings from rigorous empirical research. Brian An of the University of Iowa has found that dual enrollment programs significantly improve college degree attainment rates for low-income students, even after controlling for factors like economic and demographic background, family structure, academic standing and aspirations, and neighborhood characteristics. Researchers from AIR, evaluating the Gates Foundation’s Early College High School Initiative (which allows underserved students to earn up to 2 years of college credit in high school at little to no cost), found that participants were 20 percentage points more likely to earn a college degree than non-participants.

And, in a recent NBER working paper, researchers from the College Board and Harvard found that attaining a passing score on the AP exam increases the probability of receiving a college degree in 4 years by 1-2 percentage points per exam. Of course, students who pass an AP exam are, in general, better students than those who don’t pass the exam. To control for this, the authors used a regression discontinuity approach that compared students just above the passing threshold to those just below. While these students performed almost identically on the exam, the students who earned the score just above passing moved more quickly toward graduation.

As a result, offering opportunities for high school students to earn college credit can produce valuable longer-term benefits in college, especially for lower-income students. While many states and institutions have dual enrollment programs, a few are on the cutting edge.

The University of Texas, for example, is pioneering a free program called OnRamps that offers blended, credit-bearing courses designed by UT faculty and taught by high school teachers to students in their own schools. Georgia recently passed legislation expanding its dual enrollment offerings, which now allow high school students to take courses at in-state public universities – and earn both high school and college credit – for free. And a myriad of states waive AP exam fees for low-income students.

Dual enrollment programs, by themselves, are not enough to improve student outcomes across the board and close the opportunity gaps between different socioeconomic strata. But, as research has consistently shown, they can be remarkably effective vehicles for students to get a head start on establishing – and ultimately completing – their college educations.