In Cambodia, female entertainment and sex workers (FESWs) are one of the highest risk groups for HIV: prevalence and incidence of HIV are high, as is use of non injected amphetamine type stimulant (ATS) use. Our research there has shown that ATS contributes significantly to HIV risk. This proposed research will assess the impact of implementing new combination HIV prevention intervention options (drug abuse prevention and microfinance tools) integrated into an existing HIV prevention program (SMART girl) targeting high risk Cambodian FESWs. SMART girl provides a range of education and outreach services, especially referrals to HIV testing, and health services for sexually transmitted infections, reproductive health and family planning. It is the most widely disseminated HIV program for at risk women in the country, estimated to have contact with over one third of the country's 35,000 women engaged in entertainment work. Using a stepped wedge randomized cluster trial, we will evaluate whether our proposed SMART girl Plus program, implemented in 10 provinces over 30 months, will result in larger decreases in HIV risk compared to standard SMART girl. The intervention consists of training for and implementation of a conditional cash transfer program (CCT) aimed at ATS users within the SMART girl platform, and referrals of eligible women to a microfinance organization for financial training and resources. Women who do not use ATS (CCT and non- CCT program clients) will be eligible for referral to the microfinance organization. A second goal of this application entails the creation of an HIV Implementation Science Collaborative (HISC) in Cambodia. The HISC will link a range of governmental, academic and community-based stakeholders drawn from our groups' extensive historic and current partnerships with HIV prevention and care groups in Cambodia. The HISC mission will be to advance translational aspects of HIV prevention research in Cambodia, including by (1) providing advice and perspectives on the SMART girl Plus project; (2) participating in and promoting key sustainability activities, especially training and education opportunities in the new field of Implementation and Dissemination Science; and (3) participate in program dissemination activities aimed at sharing the research and program results within Cambodia and the broader international HIV prevention community. The proposed project will conducted by an experienced collaborative research group including from University of California San Francisco, FHI 360 Cambodia, and from Australia, the University of New South Wales. Each of these groups has over a decade each of experience and expertise in HIV prevention research, program planning and implementation in Cambodia, all in collaboration together or with other key groups in that country. The proposed implementation science project will result in significant new knowledge and potential improvements to HIV prevention practice in Cambodia.