This research career development award will provide the candidate with training in qualitative and mixed research methods and their application for understanding structural level barriers to HIV prevention in drug using populations. Prior to earning her Ph.D. in epidemiology, the candidate completed training in international politics and spent several years working in health policy positions. A unique background in international relations, health policy, and infectious disease and substance abuse epidemiology, coupled with the qualitative training proposed under this award, will prepare the candidate for independent, policy-relevant research on complex structural level barriers to HIV prevention. The career and training goals proposed under this award are to employ didactic and mentored learning to: 1) Establish expertise in the design and implementation of qualitative research studies, 2) Develop a thorough understanding of structural level barriers to HIV prevention, with a focus on drug using populations in low- and middle-income countries, 3) Gain proficiency in applying mixed methods research to understanding structural level barriers to HIV prevention, 4) Obtain further training in ethical considerations regarding research and interventions in drug using populations, and 5) Build general skills for an academic career. A key facet of the training will be to undertake a study of barriers to sterile syringe purchase among injection drug users (IDUs) in Tijuana, Mexico, where syringe purchase is legal but pharmacists are reluctant to sell syringes to IDUs. Hence, syringe sharing is common and HIV infection is on the rise. The goals of this research are to use a mixed methods approach to: 1) Characterize current practices regarding sales of sterile syringes to IDUs at pharmacies in Tijuana, 2) Identify reasons underlying refusal to sell syringes to IDUs and identify specific circumstances under which pharmacists would be willing to expand syringes sales, 3) Assess the knowledge, attitudes and beliefs of pharmacists regarding HIV/AIDS and ascertain the acceptability of providing prevention information to purchasers of syringes, and 4) Elucidate IDUs1 past experiences with pharmacy-based syringe purchase and the circumstances under which they would most likely avail themselves of pharmacy syringe sales. The candidate will apply these findings in the development of a R01 application proposing a structural level intervention to expand syringe access to IDUs in Tijuana.