Building and testing the Life Enhancement and Advocacy Programming digital training tool (LEAPLink) to better serve people with lived experience of homelessness and substance use disorder - ABSTRACT Even after they move into housing, people who have experienced homelessness (PEH) are disproportionately impacted by substance use disorder and substance-related harm. Programs supporting this population’s health-related social needs, which are known to impact the experience of substance use disorder, may help build community, improve quality of life, and reduce substance-related harm. One such evidence- based approach, the Life Enhancing Advocacy Program (LEAP), comprises a flexible, 3-step participatory process by which 3 types of activities are cocreated and stewarded with a community advisory board: a) administrative leadership opportunities through which PEH codesign programming, b) PEH-driven meaningful activities, and c) alternative pathways to recovery that are community-designed, harm-reduction oriented, and more expansive than typical substance-use treatment. However, the dissemination of such community-based participatory approaches is often stymied by the research-to-practice gap: Academic publications and conferences are inadequate vehicles to ensure these evidence-based practices are accessible and useable by providers of housing, clinical and social services. We aim to bridge this gap in this STTR phase 1 application. We plan to integrate community-based participatory and human-centered design principles in co-developing – together with PEH and a nonprofit agency that serves them – and initially testing a digital training tool for the LEAP. The resulting product for commercialization, the LEAPLink, will entail a learning management system, video-on-demand training, and synchronous consultation to help providers create a locally successful LEAP via our team’s transferrable process and framework. Our Aim 1 milestone is the LEAPLink prototype cocreated with our community advisory board that will advance for usability testing in Aim 2. Our Aim 2 milestone is to complete lab-based usability testing of the LEAPLink and achieve a System Usability Scale score of 70 or greater, which would indicate an adequate system to advance to Aim 3. Our Aim 3 milestone is to test the feasibility, acceptability, and knowledge-building capacity of the LEAPLink prototype. Successful completion of this STTR phase 1 project will provide a strong foundation for a future STTR phase 2 application for a randomized controlled trial testing the effectiveness of LEAPLink in improving provider knowledge, supporting the application of the LEAP, and building recovery capital. If successful, our team’s overarching efforts will build a strong evidence base for the successful commercialization and dissemination of the first community-driven digital training tool to help professionals in housing, clinical and social settings better support community, reduce substance-related harm, and improve quality of life for PEH with SUD.