PROJECT SUMMARY The spread of HIV in sub‐Saharan Africa has historically followed population movement within and across country borders. Nowhere is this more evident than in urban centers in South Africa, where the complex interaction between the world’s largest HIV epidemic and a legacy of forced displacement under Apartheid has resulted in a significant population of “internal migrants” (those who move within country) who bear sustained risks across the entire HIV care continuum. The majority are men who migrate to urban centers seeking employment. Not only do migrant men face intrinsic challenges associated with mobility, but they also contend with changing internal and societal constructions of masculinity influencing engagement in care. Given that men with HIV have a two-fold higher mortality rate than women, there is an urgent need to identify interventions that can effectively link and retain migrant men living with HIV to care. The current proposal leverages an established partnership between Harvard Medical School and The Health Economics and Epidemiology Research Office (HE2RO) with the goal of addressing the unique barriers experienced by internal male men living with HIV in South Africa. We will use a sequential mixed- methods design to address the following specific aims: (1) To explore, through semi-structured in-depth interviews, multi-level barriers to engagement and retention in HIV care among internal male migrants living with HIV who are not accessing care (n=30); (2) To elicit preferred HIV treatment and care attributes and service delivery features and explore characteristics driving their selection of preferred scenarios using a Discrete Choice Experiment (n=200); and (3) To co-design an intervention package with our participants and key stakeholders to promote linkage and sustained engagement in HIV care using Design Thinking. This proposal is responsive to PA-19-050, focused on “Engaging Men in HIV Testing, Prevention, and Care,” the new NIH focus on Human Mobility and HIV, and the South African National Strategic Plan for HIV and AIDS, STIs and TB. This R21 has the potential for a significant impact by generating evidence to support a multi-level intervention package to improve uptake and retention in HIV care that is responsive to the unique needs of South African migrant men in a high HIV prevalence urban setting. This multi- disciplinary team has the cross-disciplinary expertise and proven track-record of engaging hard-to-reach populations in the communities needed to execute this study.