Lesbian, gay, bisexual, and transgender (LGBT) adolescents are at increased risk for substance use, relative to their heterosexual counterparts. Although previous research has demonstrated that experiences of anti-LGBT harassment, discrimination, and victimization may explain some of this disparity, little is known about the mechanisms whereby such mistreatment leads to substance abuse. This study aimed to examine whether mechanisms suggested by the Social Development Model might explain the links between school-based victimization and substance use in this population. Five hundred and four ethnically diverse LGBT adolescents ages 14-19 reported their experiences with school victimization, substance abuse, school bonding, and deviant peer group affiliation. Anti-LGBT victimization in school was associated with substance abuse, and although causality cannot be established, structural equation modeling confirmed that the data are consistent with a theoretical model in which this association was mediated by increased affiliation with deviant peers. Preventive interventions for LGBT adolescents must not only attempt to make schools safer for these youth, but also help keep them engaged in healthy peer groups when they are confronted with mistreatment in school.