Abstract

Studies regarding school composition have been highly influential in the design of policies. However, methodological and conceptual controversies have hindered the emergence of a consensus on the existence, size, and direction of peer effects. Drawing on four cohorts of Chilean students (n = 620,044), this work analyses the extent to which the socioeconomic and academic classmates' characteristics are associated with student attainment. The findings suggest a positive medium- to low-magnitude effect of increases in the peers' academic performance. At the same time, there are almost no effects associated with changes in the classmates' socioeconomic status. These findings are stable across school types and are not driven by the sorting of students within them. The results are interpreted in the context of a new nationwide reform aiming to foster school integration and taking advantage of peer effects interaction.