Objective: To determine whether subjective social standing in school predicts a change in body mass index (BMI) in adolescent girls during a 2-year period. Design: Prospective cohort study. Setting: Self-report questionnaires from a community-based population of adolescent girls living across the United States from 1999 to 2001. Participants: Of 5723 girls aged 12 to 18 years participating in the Growing Up Today Study (GUTS), adequate information was available for 4446 (78%), who provided the analytic sample. Main Exposure: Low subjective social status in the school. Main Outcome Measures: Change in BMI between 1999 and 2001 and multivariable odds ratio for a 2-U increase in BMI in girls with low subjective social status in the school compared with girls with higher subjective social status in the school. Results: After adjusting for age, race/ethnicity, baseline BMI, diet, television viewing, depression, global and social self-esteem, menarche, height growth, mother's BMI, and pretax household income, adolescent girls who placed themselves on the low end of the school subjective social status scale had a 69% increased odds of having a 2-unit increase in BMI (odds ratio, 1.69; 95% confidence interval, 1.10-2.60) during the next 2 years compared with other girls. Conclusion: Higher subjective social standing in school may protect against gains in adiposity in adolescent girls.