OBJECTIVE: Prospective associations between obesity in adolescence and adult socioeconomic outcomes, and potential mediators, were examined in a contemporary cohort. METHODS: Longitudinal data collected in 1998 to 1999 (Project EAT-I) and 2015 to 2016 (EAT-IV) were analyzed for 1,796 participants who provided data at both time points. Adolescents (mean age = 14.8 years) self-reported demographic and psychosocial variables (EAT-I) and follow-up outcomes (EAT-IV). Body weight and height were directly measured. Bachelor's degree or more education, income >/= US $50,000, and partnered status at follow-up were examined by baseline obesity (>95th BMI percentile) using logistic regression. Self-esteem, depression, and weight-related teasing were examined as mediators using multivariate probit regressions. All analyses were adjusted for race, baseline age, and parent socioeconomic status. RESULTS: Girls with obesity were significantly less likely to have achieved a bachelor's degree (OR 0.32, 95% CI [0.18, 0.58]; P < 0.001), earn >/= $50,000 annually (OR 0.57, 95% CI [0.33, 0.99]; P < 0.04), or be partnered (OR 0.45, 95% CI [0.27, 0.75]; P < 0.002) in adulthood. No associations were observed among boys. Among girls, depression mediated 8.5% and 23.6% of the association between adolescent obesity and adult education and income, respectively. CONCLUSIONS: Adolescent girls with obesity have lower educational attainment and income and are less likely to be partnered in later adulthood. Depression may partly mediate the associations.