Young sexual minority men (YSMM) experience more victimization and are at higher risk for mental health and substance use problems compared with heterosexual youth. We attempt to understand change over time in the experience of these constructs among YSMM. Data were taken from a diverse community-based sample of YSMM (N = 450, baseline mean age 18.93) surveyed every 6 months for 2.5 years. Multilevel modeling was used to model within-person change in victimization, internalizing symptoms, externalizing symptoms, alcohol frequency, marijuana use, and illicit drug use. We tested the indirect effect of concurrent and time-lagged victimization on the association between age and mental health and substance use. Victimization, internalizing symptoms, and externalizing symptoms decreased over time. Concurrent victimization was associated with higher internalizing symptoms, externalizing symptoms, alcohol use, marijuana use, and illicit drug use. Analysis of indirect effects suggested that the association between victimization and mental health and substance use outcomes decreased as participants transitioned from adolescence into adulthood. This study found that the reduction in victimization that YSMM experience as they grow older is associated with a reduction in negative mental health and substance use outcomes. Prevention efforts to limit victimization exposure may reduce health disparities for YSMM.