Orphans and vulnerable children (OVC) in sub-Saharan Africa are at high risk for HIV infection and transmission. HIV prevention and treatment efforts with OVC are hindered by mental health and substance use problems. This randomized controlled trial compared a mental health intervention, Trauma Focused Cognitive Behavioral Therapy (TF-CBT), to an enhanced version of an existing HIV Psychosocial Counseling (PC+) program among 610 adolescents who met PEPFAR criteria for OVC and had HIV risk behaviors in Lusaka, Zambia. Outcomes included HIV risk behaviors (e.g., risky sexual behaviors), mental health (internalizing symptoms, externalizing behaviors, PTSD) and substance use. At 12-month follow-up, there were significant within group reductions in both groups for all outcomes, with the only significant between group difference being for substance use, in which OVC who received TF-CBT had significantly greater reductions than OVC who received PC+. In a subgroup analysis of OVC with high levels of PTSD symptoms, TF-CBT was superior to PC + in reducing internalizing symptoms, functional impairment, and substance use. Findings support TF-CBT for reducing substance use among OVC. Subgroup analysis results suggest that a robust intervention such as TF-CBT is warranted for OVC with significant mental and behavioral health comorbidities. The similar performance of TF-CBT and PC + in the overall sample for risky sexual behavior and mild mental health problems indicates that enhancing existing psychosocial programs, such as PC, with standard implementation factors like having a defined training and supervision schedule (as was done to create PC+) may improve the efficacy of HIV risk reduction efforts.