Adolescents who befriend drug using peers may be at risk for initiated and continued substance use. The present secondary data analysis examined how drug use homophily (i.e., similarity) in justice-involved boys’ friendship groups relates to their subsequent substance use variety across a period of five years. Participants were 1216 first-time adolescent offenders (Mage Baseline = 15.29; 100% male). Multilevel model analyses revealed that, among participants who entered the study with a history of substance use, drug use homophily was associated with greater subsequent substance use variety. Among participants who entered the study without a history of substance use, this association was no longer significant. The findings have implications for guiding justice system programming aimed at decreasing adolescent offenders’ substance use.