ABSTRACT Human mobility plays a substantial role in driving the acquisition and transmission of HIV and contributing to poor HIV care cascade outcomes. New evidence from large clinical trials shows that mobility presents a major challenge to the successful implementation of well-recognized HIV eradication strategies such as universal testing and treatment, as it can link geographically-spread epidemics, lead to introductions of HIV into communities, reduce exposure to interventions, and disrupt HIV care engagement. There is an urgent need to better understand the geospatial and temporal dimensions of mobility that lead to disparities in HIV outcomes, and for feasible and scalable interventions to improve HIV outcomes in mobile populations. Yet, research in these areas is nascent. There is a great need for an expanded scientific workforce with training in human mobility and HIV to tackle these challenges, particularly for scientists under-represented in medicine. Dr. Carol Camlin an Associate Professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at the University of California, San Francisco, and a behavioral scientist with training in social demography. Her cross-disciplinary research program has focused on the study of human mobility and HIV prevention and care outcomes. In this application for the Midcareer Investigator Award in Patient-Oriented Research (K24), Dr. Camlin proposes a comprehensive mentoring, research and career development plan which will advance the goal to reduce global disparities in HIV outcomes that result from human mobility. The overall goals of this proposal are to: 1) Expand the scope of Dr. Camlin's POR in human mobility and HIV through pursuit of training in geospatial and social network modeling methods, 2) Lay the groundwork for conducting high-quality, large-scale, theory driven interventions to improve HIV care cascade outcomes among mobile PLHIV in SSA; and 2) Engage fellows and junior faculty in the development of new multidisciplinary POR to advance HIV prevention and treatment goals among mobile populations in Africa. While the K24 provides limited resources for new research, with the support and protected time provided by the K24, Dr. Camlin will be able to leverage the existing infrastructure of her current studies to: 1) identify the geospatial networks of mobile populations and HIV “risk flows” in areas of Kenya and Uganda (Aim 1); 2) quantify the `distance decay' between clinics in origins and destinations of highly mobile persons living with HIV (PLHIV) in the settings, and assess its influence on HIV care engagement (Aim 2); synthesize cumulative findings and new developments in the field using an implementation science framework, and convene a multidisciplinary panel of experts to review and prioritize promising interventions; and develop and evaluate the potential feasibility, acceptability and appropriateness of two prototype strategies to improve HIV care engagement among...