An A-CASI survey of 197 men with a history of incarceration, ages 18-29, revealed that 50% and 17% of participants, respectively, had used substances or had sex while confined. Univariate regression analyses indicated that these two behaviors were correlated and both were associated with being older, having spent more years incarcerated, being sexual abused, and being involved with gangs and violence during incarceration. Multiple regression analyses showed that the likelihood of any substance use during incarceration was higher for men who were affiliated with a gang. Men were more likely to have had sex during incarceration if they reported having had a male sex partner in the community. The prevalence of sexual behavior also differed across sites. Findings document the occurrence of substance use and sexual behavior among incarcerated men, and highlight the need for continued research into the context of these behaviors.