PROJECT SUMMARY/ABSTRACT Strategies for effective management of HIV care and prevention exist, however many evidence-based interventions, such as Pre-exposure prophylaxis (PrEP), are not sufficiently scaled into practice, failing to reach those most in need. Implementation science (IS) seeks to bridge the gap between research and practice to ensure that evidence-based interventions are translated effectively at scale. IS methods are rapidly evolving; trainees require mentors with dedicated time and research platforms to offer opportunities to learn and apply IS methods as they work towards independent research careers. In this proposal Dr. Sheri Lippman, Associate Professor in Residence at UCSF, proposes to: 1) expand her mentoring program, including formal training to attain mentoring competencies, to improve the breathe and depth of the training she offers early career scientists; 2) expand her own program of stakeholder-engaged IS research focused on means to improving PrEP delivery to populations who are underserved through addressing clinic- and health system-based barriers to care; and 3) provide early career scientists in UCSF programs and collaborating research institutions abroad with a platform to train in IS methods. Dr. Lippman has built a research portfolio focused on social-behavioral intervention development, supporting individuals and mobilizing communities to uptake HIV testing, prevention, and care, mostly in Brazil and South Africa. The patient-oriented research in this K24 includes exploring contextual domains from the Consolidated Framework for Implementation Research (CFIR) to characterize the PrEP delivery context in clinics attending transgender women (TGW) in São Paulo, Brazil, and clinics attending adolescent girls and young women (AGYW) in Agincourt, South Africa (Aim 1). The work then includes stakeholder engaged processes to arrive at a proposed set of implementation strategies to improve PrEP service delivery that facilitates PrEP uptake and maintenance based on the taxonomies from the Expert Recommendations for Implementing Change (ERIC) Project (Aim 2). Finally, strategies will be piloted at one clinic in each site to assess feasibility, acceptability, and monitoring processes to prepare for larger trials (R01s) that evaluate whether selected strategies improve PrEP delivery, uptake, and maintenance. The research focuses on PrEP delivery for TGW in Brazil and AGYW in South Africa as both are populations who have high HIV incidence, poor engagement in HIV care, and low uptake of PrEP despite stated interest in use. Dr. Lippman has extensive collaborations, including NIH-supported work, in both areas and can ensure abundant opportunities for mentoring and stimulating new research among early career investigators in the US and both countries. In sum, this K24 provides an opportunity for Dr. Lippman to expand her IS research to address barriers to PrEP delivery in the clinic and health-system environment through implem...