Top, Bottom, and Average Achievers: A Cross-National Study of School Composition Effects in Italy and Norway

A longstanding debate in research on peer effects concerns whether exposure to high-achieving classmates enhances or depresses students’ academic performance. While normative models emphasize positive spillovers, social comparison theories highlight negative contrast effects, and empirical evidence remains mixed. Moreover, it is unclear whether peer effects operate similarly across institutional contexts. This study addresses these issues through a comparative analysis of Italy and Norway, two educational systems that differ markedly in competitiveness, tracking, evaluation practices, and gender norms. Using harmonized, population-wide administrative register data, we follow three full student cohorts from Grade 5 to Grade 8. This longitudinal design allows us to control for prior achievement—an advantage unavailable in international assessments such as PISA, TIMSS, or PIRLS. We estimate value-added school fixed-effects models that exploit within-school, across-cohort variation in peer composition. Across both countries, higher average peer achievement is associated with lower individual performance, consistent with social comparison mechanisms. Exposure to top-performing peers has negative effects, while exposure to low-performing peers has positive effects. These patterns are similar across countries and do not vary systematically by gender, suggesting that peer comparison processes are remarkably stable across institutional contexts.