Do extended school day programs affect performance in college admission tests?

We assess the effects of a Brazilian extended high school day program on college admission test scores. The program entails an increase in Math/Science and Language class time, and the introduction of extra-class activity time. We exploit variation in program implementation timing to apply a difference-in-differences strategy and an event-study approach. Results show positive large effects on test scores and suggest that these effects are likely driven by increased class and extra-class activity hours. Moreover, the program affects not only scores in subjects for which it contemplates increased class time, but also in Humanities. Finally, we are able to show that increased time dedicated to academic-related extra-class activities works as a multiplier of program effects. In fact, these additional hours spent in complementary activities make the magnitude of program effects double from 0.092-0.150 to 0.180-0.317 standard deviation.