Both surveillance and behavioral epidemiological studies show that young male sex workers (YMSWs) in Vietnam have high rates of unprotected sex with multiple, concurrent partners - including both male and female partners - contributing to high rates of STIs and HIV and amplifying already high HIV incidence. Exposure to existing prevention programming is low, with major gaps in HIV knowledge and sexual risk reduction skills. Existing community outreach activities have primarily reached gay-identified YMSM. Moreover, owing to profound risk for stigma and discrimination in health care settings, few YMSW are engaged and retained in protective health services (including STI/HIV screening, HBV/HPV vaccination, and early linkages to HIV care). Our collaborative US/Vietnam research team has been conducting NIDA-funded HIV research among high risk youth populations, including YMSWs, for the past eight years. Building on the substantial research capacity and health services infrastructure that has been achieved in our prior work, we propose to address these gaps in community outreach and health services access by implementing a composite intervention package targeted to YMSWs in the two strategically selected cities in Vietnam (Hanoi and Ho Chi Minh City). Using Sexual Health Promotion as a conceptual framework, we will combine already proven intervention technologies - community outreach nursing and sexual health promotion interventions - to enhance outreach coverage and to foster engagement and retention in health services. Significant levels of outreach coverage will be achieved (with an estimated 12,000 outreach contacts) and substantial numbers of health services will be delivered (2,400 health services participants). Using a mixed-methods approach that includes anthropological ethnography, social and behavioral epidemiology, and health services assessments, process and outcomes evaluation of both the community outreach and health services intervention will be undertaken. Repeated cross-sectional surveys, administered both prior to and following implementation of the community outreach and health services intervention, will document community-level increases in exposure to outreach, increased knowledge and awareness of behavioral HIV risk, increased sexual risk reduction skills and participation in the clinic-based sexual health promotion intervention, thus demonstrating effective engagement and retention in health services. Of particular interest to implementation science, both qualitative and quantitative analysis will assess between-city differences in intervention uptake and effectiveness, data that will inform our understanding of the impact, adaptability, and generalizability of the intervention and guide future dissemination.