7. PROJECT SUMMARY/ABSTRACT India’s HIV epidemic is being fueled by an alarming rise in injection of opioids. Young people who inject drugs (YPWID; 18-29 years of age) are poorly engaged in treatment for opioid use disorder and HIV prevention services and bear a disproportionate burden of new HIV infections. Increasing engagement in treatment for opioid use disorder and uptake of HIV prevention services among YPWID is an urgent public health priority. YRGCARE, an Indian non-governmental organization, has established Integrated Care Centers in 8 cities to deliver medications for opioid use disorder (MOUD) and other HIV prevention services, including HIV testing, clean needles, and condoms to people who inject drugs. YPWID initiating MOUD at Integrated Care Centers engage poorly in treatment due to diverse barriers that also limit uptake of HIV prevention services. YPWID under-engaged in MOUD have high risk behaviors, low HIV testing, and high HIV seroconversion. Few interventions exist to support substance use treatment and HIV prevention among Indian YPWID. Dr. Ganapathi is a pediatric infectious diseases physician who aspires to lead rigorous research to address this gap. Building upon her HIV research fellowship training and unique clinical background, she will utilize this Mentored Patient-Oriented Research Career Development (K23) Award to: 1) develop expertise in behavioral intervention development, 2) gain skills in advanced statistical methods and study design for intervention research, and 3) develop an understanding of the principles of implementation science. Dr. Ganapathi will develop and pilot “Yuva Sath”, a brief, peer-led behavioral intervention to support MOUD engagement and uptake of HIV prevention services among YPWID who have initiated MOUD at Integrated Care Centers but are under-engaged in treatment. Informed by empirical principles used in successful youth- tailored interventions, Yuva Sath will be developmentally tailored, leverage peer support, and employ convenient mobile phone delivery. Development of Yuva Sath will entail adapting “Life-Steps”, an empirically supported problem-solving intervention originally developed to support antiretroviral therapy adherence. Intervention development will be informed by: 1) analysis of existing quantitative data collected from a retrospective cohort of YPWID initiating MOUD across 8 Integrated Care Centers, and 2) collection of qualitative data to understand YPWID preferences for intervention content and delivery. Dr. Ganapathi will then conduct a pilot randomized controlled trial of Yuva Sath, compared to usual care, among YPWID at a single Integrated Care Center in Aizawl city in Northeast India, to inform a future fully powered effectiveness trial. Leveraging research infrastructure at Harvard Medical School and YRGCARE, Dr. Ganapathi will be mentored by a multidisciplinary team, with expertise in behavioral medicine, infectious diseases, and addiction medicine, led by Drs. O’...