Background: HIV/AIDS has the potential to become a leading cause of death in Nepal. The around 30,000 street youth here are especially vulnerable to HIV as they share characteristics with and closely interact with higher risk groups. While international studies of street youth have surfaced important demographic, historical, and severity of homelessness predictors, modifiable psychosocial predictors have not been identified in this population. Due to the interpersonal nature of HIV transmission and to the complex intertwined social networks of these youth, consideration of such factors is essential. Objectives: To establish whether modifiable psychosocial constructs independently predict behavioral risk for HIV in Nepalese street adolescents, and to make street- and culturally sensitive recommendations for reducing their exposure to the HIV virus. Methods: Three hundred and seven 15-24 year old street-living, street-working and street-transiting males were recruited from primarily street locations in Kathmandu, Nepal, to complete a closed-ended orally-administered questionnaire.Results: This study captured one of the highest risk sub-groups of street youth in Nepal. Sixty-four percent of sexually active respondents had ever had a known HIV positive, injecting drug using, or commercial sex partner, 56% had ever had anal sex, survival sex, forced sex, or sex while intoxicated, and 78% had had at least one of any of these. Only 30% and 13% reported consistent condom use with commercial and non-regular partners, respectively. Twenty-three percent of youth had ever injected drugs, and of these, 65% had shared needles. Multivariate logistic regression showed area interviewed, older age, history of sexual abuse, longer time since leaving home, higher risk activities with peers, difficulty meeting food needs, lack of connection to an NGO worker, perception that more peers have had sex, less social support, and less self-efficacy to use condoms to all predict HIV risk.Conclusion: In addition to demographic, historical, and severity of homelessness variables, modifiable psychosocial factors were important predictors of HIV risk. These youth’s greatly increased risk of exposure may be buffered by social strategies such as preventing risky peer group norms, building bonds between NGO staff and street youth, and facilitating development of their assertiveness and negotiation skills.