This article uses the mass migration wave to Israel in the 1990s to examine the impact of immigrant concentration during elementary school on the long‐term academic outcomes of native students in high school. The results suggest that the overall presence of immigrants in a grade had an adverse effect on the chances of passing the high school matriculation exam, which is necessary to attend college. This result is robust to a variety of alternative specifications. We also perform a ‘placebo’ analysis which shows that the high school outcomes of natives are affected only by the immigrant concentration in their own 5th grade class.