OBJECTIVES: To examine the effect of a 15-session coping group intervention compared with a 15-session therapeutic support group intervention among HIV-positive men and women with a history of childhood sexual abuse (CSA) on sexual transmission risk behavior. DESIGN: A randomized controlled behavioral intervention trial with 12-month follow-up. METHODS: A diverse sample of 247 HIV-positive men and women with histories of CSA was randomized to 1 of 2 time-matched group intervention conditions. Sexual behavior was assessed at baseline; immediately after the intervention; and at 4-, 8-, and 12-month follow-up periods (5 assessments). Changes in frequency of unprotected anal and vaginal intercourse by intervention condition were examined using generalized linear mixed models for all partners, and specifically for HIV-negative or serostatus unknown partners. RESULTS: Participants in the HIV and trauma coping intervention condition decreased their frequency of unprotected sexual intercourse more than participants in the support intervention condition for all partners (P < 0.001; d = 0.38, 0.32, and 0.38 at the 4-, 8-, and 12-month follow-up periods, respectively) and for HIV-negative and serostatus unknown partners (P < 0.001; d = 0.48, 0.39, and 0.04 at the 4-, 8-, and 12-month follow-up periods, respectively). CONCLUSION: A group intervention to address coping with HIV and CSA can be effective in reducing transmission risk behavior among HIV-positive men and women with histories of sexual trauma.