Project Summary/Abstract The U.S. Ending the HIV Epidemic (EHE) plan aims to reduce new HIV infections by 90% by 2030 through providing pre-exposure prophylaxis (PrEP) for those at risk for HIV and antiretroviral therapy (ART) for those with HIV. The EHE does not integrate substance use disorder (SUD) assessments and treatments nor provide implementation strategies on providing PrEP/ART for persons who use drugs (PWUD) involved in the justice system, a critically underserved population. In response to RFA-DA-24: Ending the HIV Epidemic: Focus on Justice Populations with SUD (R61/R33), our proposed study titled STOP (Shared decision making to Treat Or Prevent) HIV in Justice Populations is a 5-year project; the first year (R61) is dedicated to a single site pilot study in CT, followed by a 4-year, 4 site (CT, KY, and 2 in TX) type 3 hybrid implementation-effectiveness study (R33). We build on existing partnerships between our multi-disciplinary research teams, justice and community agencies, and stakeholders with lived experience, to develop and assess a patient-centered approach to access PrEP/ART/SUD services. Following a differentiated service delivery model implementation approach, we focus on incorporating (1) risk assessments conducted by patient navigators (PN) and (2) providing patient choice (PC) options for services delivery methods (e.g., brick and mortar clinic, telehealth, mobile health unit) to access PrEP/ART/SUD; this enhanced implementation approach will be compared to routine PN alone and include implementation and participant outcomes. Aim 1 (R61) is to develop and pilot test the PN+PC menu of options of PrEP/ART and SUD treatment services for justice-involved PWUD compared to established PN in CT, which will be achieved by meeting the following milestones: (1) build upon established collaborations to include multiple service delivery models and the perspectives of persons with lived experience; (2) curate a menu of PC options to access PrEP/ART and SUD services; (3) conduct a pilot study that includes among N=30 adults with recent justice system involvement with DSM-5 SUD at risk or living with HIV, randomized 1:1 to PN vs. PN+PC to assess acceptability, feasibility, and proportion who (a) access a clinician and (b) receive treatment (ART, PrEP, SUD, harm reduction); (4) seek guidance from the Patient Engagement Resource Center to inform the final implementation model of the R33; (5) develop a common set of R33 measures; and (6) obtain R33 IRB/OHRP approval. Aim 2 (R33) will use R61 data to inform our type 3 hybrid implementation-effectiveness study of PN vs PN+PC in 4 communities (CT, 2 in TX, KY) using the R61 eligibility criteria, with Aim 2. 1 evaluating patient- level outcomes (proportion accessing clinicians and treatment) and Aim 2.2 assessing system-level implementation outcomes (acceptability, adoption, penetration), sustainment, and costs of implementing both PN and PN+PC approaches. This study has the potential to be...