Removing barriers to college credits: Where and for whom AP exam fee waivers work

We study the effects of North Carolina’s Advanced Placement (AP) exam fee-waiver policy on exam participation and potential college-credit attainment conditional on AP enrollment. Using student-course level administrative data, we first exploit within-student variation among students enrolled in multiple AP courses during both pre- and post-waiver periods. We find that fee waivers increased exam participation by 2.1 percentage points but did not significantly increase the share of AP enrollments yielding an exam score of 3 or higher, a common threshold for college-credit eligibility. This average null, however, masks a 3-percentage-point increase in the share of low-SES AP enrollments yielding a score of 3 or higher, narrowing the baseline attainment gap by 15 percent. Using the full sample of AP enrollments and a difference-in-differences framework, we then show that enrollments with the lowest predicted exam-taking propensity absent the waiver experienced the largest gains in both exam participation and potential college-credit attainment, suggesting that universal fee waivers generate larger benefits where barriers to AP exam participation are most likely to bind. Under illustrative assumptions, our welfare calculations indicate that the policy’s benefits far exceed its costs.