We investigate how the intensity of Ramadan affects educational outcomes by exploiting spatio-temporal variation in annual fasting hours. Longer fasting hours are related to increases in student performance in a panel of TIMSS test scores (1995–2019) across Muslim countries but not other countries. Results are confirmed in a panel of PISA test scores (2003–2018) allowing within country-wave comparisons of Muslim to non-Muslim students across Europe. We provide evidence that a demanding Ramadan affects PISA test scores of Muslim students only in cohorts with a large share of co-religionists. This finding is consistent with the hypothesis that shared experiences during more intensive Ramadans facilitate the formation of social capital and a social identity conducive to learning outcomes.