We provide evidence that short-term shocks to student cognitive performance have long-lasting consequences for human capital development. We use administrative data from Mexico City to show that students’ exposure to violent crime in the week immediately prior to a high-stakes exam lowers females’ test scores by 11% of a standard deviation. As a result, 19% of female students exposed to violent crime are subsequently assigned to less preferred, lower-quality high schools. We find no such effect for males and show that crime-induced concentration problems are an underlying mechanism behind the detrimental effects on females’ test scores.