Social Closure in U.S. High Schools? Patterns and Determinants of Socioeconomic Segregation in Adolescent Friendship Networks

Adolescent friendship networks exhibit limited interaction across socioeconomic and racial lines. Using Add Health data and a novel exponential random graph model, this study examines socioeconomic segregation in high school friendships and its relationship to racial segregation. Results show that networks are segregated less by socioeconomic status (SES) than by race, yet low-SES students are excluded from high-SES circles to a similar degree. Crucially, unlike racial segregation, which is mutual, socioeconomic segregation is unilateral: many ties from low-SES to high-SES peers go unreciprocated. A decomposition of determinants shows about 60 percent reflects differences in schools’ socioeconomic composition, while 40 percent arises from within-school friendship choices. Within schools, segregation arises less from SES-stratified courses and extracurriculars than from racial homophily, SES-based popularity differences, and triadic closure. Thus, while between-school compositional differences limit who can meet, within schools, segregation is shaped more by students’ preferences and network processes than by meeting opportunities.