The authors consider the effect of legal access to alcohol, which is known to increase drinking behavior, on academic performance. The preferred approach instead exploits the longitudinal nature of the data, essentially identifying the effect by comparing a student’s academic performance before and after turning 21. It is found that students’ grades fall below their expected levels upon being able to drink legally, but by less than previously documented. We also show that there are effects on women and that the effects are persistent. The main results are robust to the inclusion of individual fixed effects, individual trends, and individual quadratics, in addition to other controls, that account for the expected evolution of performance as students make progress towards their degrees.