ABSTRACT Since 2008, countries in Sub Saharan Africa have seen rapid increases in injection drug use including injection of heroin and cocaine [1-11] resulting in high prevalence of HIV and HCV infection, particularly in Tanzania and Kenya [1, 12, 13]. Uganda also has seen an increase in people who inject drugs [14-16] with recent estimates at approximately 4000 in Kampala [17]. HIV prevalence among PWID in Uganda is estimated to be around 17% in multiple studies [14, 17], with heroin being the most commonly injected drug. Despite the serious risk, interventions to reduce the harms associated with injection drug use and drug related sexual risk are just beginning to be developed and implemented in the region. Most researchers argue that a combination of approaches are needed to reduce HIV infection among PWID including: provision of clean syringes through syringe exchange programs (SEPs); frequent HIV testing and linkage to HIV care; antiretroviral therapy initiation after infection to reduce risk of onward transmission through viral suppression; medication assisted therapy; psychosocial support and pre- and post-exposure prophylaxis [22-24]. In the proposed application, we will collaborate with the Uganda Harm Reduction Network and Makerere University School of Public Health to develop, refine and pilot for feasibility and acceptability a combination HIV prevention intervention for PWID in two harm reduction Drop In Centers (DICs) in Kampala. We will use implementation science methods, the Consolidated Framework for Intervention Research (CFIR), to develop the intervention so that it can be feasibly implemented and sustained using the resources in DICs. The intervention will use social network HIV/HCV testing to bring PWID into the DICs. Participants will be given a small stipend for receiving HIV and HCV testing, and those who inject heroin will be offered naloxone, buprenorphine, a self-directed computer- based drug treatment program, CBT4CBT, and will complete a short interview to identify other PWID and receive coupons to recruit them for HIV/HCV testing. Participants will also be offered an array of services already offered in the DICs including syringes and other safe injection supplies, PrEP, and condoms. Finally, those who are HIV positive will be assigned a peer navigator who will link them into care and ensure continued attendance to HIV clinics and ART adherence. Specific aims of the proposed project include the following: 1) To develop a combination HIV prevention intervention for PWID in Kampala Uganda, using the Consolidated Framework for Intervention Research; 2) To refine the intervention through implementation cycles using the CFIR framework to identify barriers and find solutions to implementation and scale-up; 3) To assess feasibility, acceptability and initial promise of the intervention with a 6-month pilot test. We will collect quantitative implementation outcomes including the numbers of people tested for HIV/HCV, uptake o...