Tookes’ Supplement Request Abstract Most Americans with OUD remain out-of-treatment. Over the past three decades, rates of opioid use, OUD and overdose have skyrocketed. Medications for opioid use disorder (MOUD), including methadone and BUP, are the first-line OUD treatments; however, in 2019, after years of Medicaid expansion and MOUD implementation initiatives, only 1 million of the 7.6 million persons in the US in need of OUD treatment received MOUD, leaving a large treatment gap. Barriers to MOUD are often structural, including availability, health system fragmentation, wait times and healthcare providers’ stigma toward people who use drugs (PWUD). Therefore, structural interventions are needed to increase MOUD access and use. BUP treatment is associated with large reductions in overdose-related mortality. However, strong racial/ethnic and geographic disparities in BUP access have emerged with marginalized groups have more limited access to care. “Low-threshold” BUP models seek to increase BUP access by offering same-day treatment entry, flexibility, harm reduction counseling, and availability in unconventional settings, such as emergency departments, mobile units, or harm reduction agencies. The proposed study, Low-threshold buprenorphine treatment at syringe services programs: a Type I hybrid effectiveness-implementation trial, targets structural barriers to BUP treatment (e.g., health system fragmentation, waiting lists, and medical providers’ stigma towards people with OUD) by integrating BUP treatment into syringe services programs (SSPs). Dr Hansel Tookes from the Florida Node Alliance will serve as Co-Lead Investigator and will dedicate effort to protocol development activities.