Project Abstract In view of the continued disproportionate rates of HIV infection among Black men who have sex with men (MSM), there is an urgent public health need to identify scalable interventions to support Black MSM at risk of HIV to decide to take pre-exposure prophylaxis (PrEP), help access PrEP, and adhere to PrEP. Currently, Black MSM have the highest rates of HIV acquisition in the United States yet have the lowest rates of PrEP utilization. Innovative methods to support use of this lifesaving medication are few and those that are available are seldom rigorously tested. One intervention demonstrated in early studies to have potential for positive impact a client-centered care coordination (C4) intervention model. C4 was piloted in the NIH-funded HIV Prevention Trials Network (HPTN) 073 study and showed promise, yet more evaluation is required to assess and leverage this intervention. The aims of this study are to further the work done in HPTN 073 with regard to C4 in real-world clinical settings in Washington, DC and in New York City. Aim 1 will determine the efficacy of C4 for increasing PrEP adherence among Black MSM, Aim 2 will identify the optimal dose of C4 implementation for maximizing its effect on PrEP adherence, and Aim 3 will d Describe the acceptability and feasibility of C4 implementation in community settings. Findings from this study will contribute to the NIH priorities to reduce HIV incidence as well as cross-cutting areas of using implementation science to contribute to our understanding of structural and psychosocial barriers to care and reduction of healthcare disparities.