Policy-makers have cited menstruation and lack of sanitary products as barriers to girls' schooling. We evaluate these claims using a randomized evaluation of sanitary products provision to girls in Nepal. We report two findings. First, menstruation has a very small impact on school attendance: we estimate that girls miss a total of 0.4 days in a 180 day school year. Second, improved sanitary technology has no effect on reducing this (small) gap: girls who randomly received sanitary products were no less likely to miss school during their period. We can reject (at the 1% level) the claim that better menstruation products close the attendance gap.