Health-compromising lifestyles involve stable patterns of behavior, are associated with social environments of high risk, and accelerated developmental trajectories. Developmentally, antisocial behavior is associated with such lifestyles. Mediational prediction models to a measure of lifetime average sexual risk behavior assessed over a 10-year period (ages 13-14 to 22-23 years) were examined for a sample of at-risk, young men. The measure included years of abstinence from intercourse as well as levels of 3 key heterosexual indicators of risk; namely, frequency of intercourse, number of intercourse partners, and condom use. Predictors included lifetime average measures of contextual, family and peer process, and individual behaviors. In addition, similar models for prediction to STD contraction were assessed. A younger age of onset of intercourse was associated with higher numbers of intercourse partners after onset. As hypothesized, findings indicated mediational associations of SES, parental monitoring, deviant-peer association, antisocial behavior, and substance use in predicting to sexual risk behavior. Lower condom use also predicted to STD contraction.