PROJECT SUMMARY People who are releasing from jail or prison are at disproportionately high risk of acquiring HIV. This population also has high prevalence of mental health or substance use disorders, which can further increase HIV risk. While robust services and targeted resources have improved outcomes for people living with HIV when they release from jail or prison, the larger numbers of people at high risk for HIV upon release have fewer resources available to support them. Consequently, there is a need for low-cost, scaleable ways to connect these individuals with HIV prevention services including pre-exposure prophylaxis (PrEP). Behavioral economics approaches, including nudges (small processes or heuristics that encourage engagement in healthy behavior; for example, auto-enrollment in services), may provide a low-cost and effective way to increase service engagement. However, introducing nudges necessitates an in-depth understanding of the choice architecture of incarcerated or recently released individuals. In addition, identifying high-risk individuals, linking them with services, and implementing nudges requires knowledge of the complex and intersecting systems in which individuals receive services. Accordingly, we propose to conduct formative work to map existing services, service gaps, and key decision points for people at high risk for HIV upon release from prison or jail. Our experienced, interdisciplinary project team includes two clinical researchers with expertise in HIV prevention (Graham) and correctional health (Jack), a behavioral economist (Hauber), a qualitative research expert (Starks), and an implementation scientist (Weiner). The core team will also include a Project Manager, a person with lived experience accessing HIV prevention services who has worked for a community-based organization serving this population. We will conduct semi-structured in-depth interviews with Washington jail and prison staff and providers (n=15), community-based service providers (n=20), and recently released people (n=15). The Consolidated Framework for Implementation Research (CFIR) will inform the provider interview guide and analysis, facilitating systematic assessment of implementation opportunities and challenges. Nudge theory will inform analyses of the decision-making processes of service users. We will focus this formative work on services within and people releasing to King County, Washington State’s most populous county and an EHE focus site. The formative work we propose is essential for understanding community needs and strengthening relationships with service providers to enable robust community engagement with future research or implementation. After this formative work, we will be well positioned to seek future funding to develop and conduct discrete choice experiments (DCEs) to assess provider and service user preferences for service package components and implementation strategies designed to nudge people toward PrEP uptake an...