Contemporary HIV prevention efforts are increasingly focused on those already living with HIV/AIDS (i.e., "prevention with positives"). Key to these initiatives is research identifying the most risky behavioral targets. Using a longitudinal design, we examined socio-demographic and psychosocial factors that prospectively predicted unprotected anal intercourse (UAI) in a sample of 134 HIV-seropositive men who have sex with men (MSM) initiating, changing, or re-starting an antiretroviral therapy regimen as part of a behavioral intervention study. Computer-based questionnaires were given at baseline and 6 months. In a sequential logistic regression, baseline measures of UAI (step 1), socio-demographic factors such as Latino ethnicity (step 2), and psychosocial factors such as crystal methamphetamine use, greater life stress, and lower trait anxiety (step 3) were predictors of UAI at 6 months. Problem drinking was not a significant predictor. Prevention efforts among MSM living with HIV/AIDS might focus on multiple psychosocial targets, like decreasing their crystal methamphetamine use and teaching coping skills to deal with life stress.