In this paper, we present data from an evaluation of the educational impact of a school breakfast program implemented in rural schools in Peru. The results showed positive effects on school attendance and dropout rates, and a differential effect of the breakfast program on multiple-grade and full-grade schools. Particularly in multiple-grade schools the program shows a significant and positive effect on short-term memory, arithmetic and reading comprehension. The evaluation also showed an unexpected negative consequence: students in the breakfast group reduced their time in the classroom with their teachers and increased the time in recess (when they consumed the breakfast).