Millions of migrants from Eastern Europe have sought better opportunities in Western European countries, yet few studies have assessed the impact of such moves on these migrants' children. This study implements a causal inference design relying on propensity score matching in order to isolate a causal effect of migration on children’s educational outcomes. It analyzes PISA test scores from 2012, 2015, and 2018 for children born in twelve Eastern European countries and living in eight Western European countries. Compared to their counterparts who remained in their countries of origin, migrants score lower. Once immigrant children are matched to non-immigrants with similar propensities to migrate -- estimated based on family and socioeconomic background -- the disparity for math scores disappears, while those for reading and science remain. In addition, children who migrate from within the EU, at older ages, and who are female face greater disparities.