Severely Mentally Ill (SMI) adults have disproportionately high HIV seroprevalence rates. Abuse of alcohol and other substances 6(AOD) and lifetime exposure to trauma by others are particularly potent risk factors, which, in combination with psychiatric disabilities, create triple jeopardy for HIV infection. This study examined the predictive utility of demographic characteristics; history of physical, emotional, or sexual abuse; extent of drug and alcohol abuse; knowledge about HIV/AIDS; sexual self-efficacy; and condom attitudes toward explaining the variance in a composite of HIV high-risk behavior among 188 SMI women and 158 SMI men. History of sexual abuse, engaging in sexual activities while high on substances, and lower cannabis use were the most significant predictors of HIV sexual risk behaviors. Given the triple jeopardy for HIV risk in this population, a triple barreled approach that simultaneously addresses multiple health risks within an integrated treatment setting is warranted.