Many schools have recently experimented with moving breakfast from the cafeteria to the classroom. We examine whether such a program increases achievement, grades, and attendance rates. We exploit quasi-random timing of program implementation that allows for a difference-in-differences identification strategy. We find that providing breakfast in class relative to the cafeteria raises math and reading achievement by 0.09 and 0.06 standard deviations, respectively. These effects are most pronounced for low-performing, free lunch-eligible, Hispanic, and low body mass index students. A lack of differences by exposure time and effects on grades suggest that these impacts are on test-taking performance rather than learning. At the same time, the results highlight the possibility that measured achievement may be biased downwards, and accountability penalties may be inappropriately applied, in schools where many students do not consume breakfast.