Young men who have sex with men (YMSM) are disproportionally affected by HIV in the United States, accounting for nearly half of new HIV diagnoses among MSM. Pre-exposure prophylaxis (PrEP) has demonstrated high levels of efficacy for HIV prevention; however, uptake has been suboptimal with uptake barriers including cost; stigma; not wanting to take a daily pill; and difficulty locating providers. New PrEP options are now available for YMSM and have the potential to address many of barriers to PrEP uptake, especially non-daily options which are preferred by many YMSM. In this proposal, we will assess decision support needs of YMSM through formative work with YMSM and key stakeholder, and develop a novel mHealth decision support tool to support PrEP uptake of one of four PrEP regimens: daily oral TDF/FTC or TAF/FTC; on-demand (2-1-1) TDF/FTC; and CAB-LA. PrEP Choice will provide PrEP information and comparison charts between the four regimens; PrEP testimonials; and information about access resources. In Aim 1, we will assess decision support needs of YMSM through focus groups and individual interviews with YMSM, and PrEP prescribers and PrEP navigators, key stakeholders for this population. In Aim 2, we will use an iterative development strategy to develop the PrEP Choice tool with YMSM and key stakeholders. Upon project completion, we will have developed a novel decision support aid for PrEP uptake among YMSM. This project will provide mentored research training and support collection of preliminary data for further development and pilot testing in a R34-level grant submission.