PROJECT SUMMARY/ABSTRACT As many as 50% of people with HIV (PWH) are not in regular HIV primary care in the U.S. This is particularly common for PWH who use substances such as cocaine, methamphetamines, and opioids. PWH who are not consistently retained in care are at risk for: delayed antiretroviral treatment (ART) initiation, reduced ART adherence, unsuppressed viremia, and mortality. Moreover, poor retention means effective ART cannot be leveraged to prevent further HIV transmission. The long-term goal is to develop impactful, brief intervention techniques that can be easily integrated into usual care practices to enhance HIV care retention. The objective of this proposal, which is the next step in attaining the long-term goal, is to adapt and refine an existing retention intervention in the context of an open trial and a small randomized controlled trial. We will adapt a brief, 2-session acceptance-based behavioral therapy (ABBT) intervention to enhance retention in HIV care for people who use substances by targeting stigma. ABBT promotes an accepting stance towards life’s challenges and encourages participants to thoughtfully disclose the serostatus and/or substance abuse problems as a behavioral step towards challenging stigmatization fears. The central hypothesis is that increased tolerance of stigmatization, facilitated through increased acceptance of HIV status and substance abuse behaviors, will increase PWH’s longitudinal commitment to care. The aims of this proposal are: (1) To use an iterative process to refine ABBT for substance using, out-of- care PWH by conducting an open trial in English-speakers (n=7) and monolingual Spanish speakers (n=3); and, (2) To conduct a pilot randomized controlled trial (n = 50; incl. 10 Spanish speakers) of ABBT vs. Treatment-as-Usual (TAU). Primary outcome will be retention in care. The sample will consist of 60 HIV patients who have not attended a medical visit in at least 9 months at our infectious diseases clinic in Providence, R.I. The approach is innovative in that it departs from the status quo by using brief acceptance- based psychotherapy techniques, delivered by telehealth, to increase acceptance of HIV status and substance abuse problems and promoting careful and thoughtful disclosure as a specific mechanism to support retention. Additionally, ABBT will be adapted for monolingual Spanish speakers as this cohort of PWH needs more research attention. Upon successful completion of the proposed R34 research, this study will contribute significant actionable data that will lay the groundwork for a large-scale investigation of ABBT for out-of-care PWH who use substances.