Since the end of the Cold War, 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 Programme for International Student Assessment (PISA) scores from 2012, 2015, and 2018 for children born in Albania, Estonia, Poland, Romania, Russia, and the seven Former Yugoslavian countries and living in Austria, Denmark, Finland, Germany, Luxembourg, the Netherlands, Switzerland, and the United Kingdom. Compared to their counterparts who remained in their countries of origin, migrant children attain lower reading, math, and science scores. 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. Children who migrate from within the EU, at older ages, who speak a foreign language at home, and who are female face greater disparities. This paper shows the need for policymakers and educational administrators to better handle the negative academic effects that migration can have on children from within Europe.