Project Summary South Africa (SA) has the highest number of people living with HIV in the world (PLWH) and a high burden of untreated substance use disorder (SUD), which contributes both to poor engagement in HIV care and HIV transmission. Internalized substance use (SU) stigma is barrier to PLWH engaging in both HIV care and treatment. Integrating peer recovery coaches (PRCs)—or persons with lived SUD experience—into existing teams aiming to re-engage PLWH in HIV care may be a promising way to reduce internalized SU stigma among PLWH who have fallen out of care, and consequently, increase retention in HIV care and SUD treatment. Yet, despite the prevalent assumption that PRCs reduce internalized SU stigma, few studies have examined this quantitatively, and none have examined this in the context of HIV care. Further, although PRC models have been rapidly scaled in the US, little research has examined PRC models in low- and middle-income countries. In an ongoing study (R21DA053212), our team is evaluating the feasibility and acceptability of a PRC model integrated into existing HIV retention teams, and its preliminary effectiveness in shifting health worker stigma towards substance use and improving patient HIV care engagement. Adding to this ongoing study, the overall aim of this proposal is to evaluate the preliminary effectiveness of this PRC model in shifting patient internalized SU stigma and to examine if patient internalized SU stigma is associated with engagement in SUD treatment along with HIV care for PLWH and SUD who have fallen out of HIV care (n=50). Our conceptual model integrates the Stage Model of Self-Stigma and the situated-Information Motivation Behavioral Skills Model of Care Initiation and Maintenance framework. We propose three aims: (1) First, we will evaluate if PRCs shift internalized SU stigma among PLWH with SUD who have fallen out of HIV care by comparing changes in internalized SU stigma scores of patients receiving care from the PRC integrated re-engagement team to a matched non-PRC re- engagement team between baseline and follow-up (about six-months post-baseline) assessments. (2) Next, we will evaluate if changes in internalized SU stigma are associated with HIV care and SUD treatment engagement over six-months via HIV clinic and SUD treatment attendance records. (3) Our final aim will be to capture patient perspectives on how internalized SU stigma and other intersecting stigmas relate to HIV/SUD care engagement, and how these may be related to PRC contact, by qualitatively interviewing patients receiving care from the PRC integrated re-engagement team. This study will use the existing infrastructure of ongoing study R21DA053212. Findings will inform future efforts to evaluate scalable SU stigma reduction interventions to improve HIV and SUD care engagement for PLWH with SUD. This project will additionally enable the PI’s pursuit of becoming an independent researcher focused on designing and adapting interventions ...