"This paper uses the mass migration wave to Israel in the 1990s to examine the impact of immigrant concentration in elementary school on the long-term academic outcomes of native students in high school. To identify the causal effect of immigrant children on their peers, we exploit random variation in the number of immigrants across grades within the same school. The results suggest that the overall presence of immigrants had essentially no effect on the quality of the high school attended by native Israelis and on dropout rates, and at most a mild negative effect on high school matriculation rates. However, when we break up the sample by parents' education and by ethnic origin, we find that disadvantaged children were more likely to have been adversely affected by a higher immigrant concentration in elementary school. Focusing on the impact of Ethiopian immigrants who are from a much lower socio-economic background, we find stronger evidence of adverse effects, especially for disadvantaged students and in classes where immigrant concentration was particularly high"--National Bureau of Economic Research web site.