Peer Diversity Shocks: Evidence from the Amsterdam Secondary-School Matching.

Schools are among the first social settings in which children regularly interact with peers from different backgrounds, yet estimating the effects of such exposure is difficult because families sort into schools. I study Amsterdam’s centralized secondary-school assignment system and exploit lottery-induced variation in peer diversity to examine whether exposure to outgroup peers affects intergroup friendship formation and subjective outcomes related to diversity and school life. I measure exposure using a recentered diversity shock, defined as the difference between the outgroup share students are assigned to and the outgroup share they could expect given their application list. In doing so, I test a central prediction of intergroup contact theory: does exposure to more diverse peer environments foster outgroup friendships and more open attitudes?