PROJECT SUMMARY Black and Latinx people who use opioids (PWUO) bear a disproportionate burden of opioid overdose deaths. The economic burden faced by Black and Latinx PWUO has also risen due to costs associated with excess mortality and utilization of high-cost healthcare services. Compared to White PWUO, Black and Latinx PWUO are less likely to be initiated on buprenorphine in emergency department (ED) settings and establish care in primary care for the treatment of opioid use disorder (OUD). Racial disparities among PWUO in primary care are driven by social determinants of health (SDH; e.g., lack of peer support or health insurance) and may be partially addressed by adopting innovative mobile health and peer coaching strategies. With NIH support, we have validated a theory-driven, artificial intelligence (AI)-driven texting tool using natural language processing to facilitate real-time text responses to patient queries combined with automated texts facilitating receipt of buprenorphine in office-based opioid treatment (OBOT) and social services that address social determinants of health (SDH). This open source texting tool offers passive reminders, informational content, and interactive two- way response algorithms without personal staff contact. In addition, we have adapted an efficacious cultural and structural humility training for PRCs that goes beyond SDH to also address stigma reduction, discrimination, health habitus, and patient navigation to enhance uptake of primary care and social services for PWUO. Using a three-arm, comparative effectiveness trial design, our specific aims are to: (1) Assess the efficacy of PRC- supported text-based care/services coordination with PWUO + AI-driven SDH-enhanced text messaging (intervention arm-1) vs. AI-driven SDH-enhanced text messaging only (intervention arm-2) vs. TAU or printed social/medical services referrals (control) to enhance the receipt of buprenorphine in OBOT among ED-enrolled Black / Latinx PWUO (N=252); (2) Evaluate the implementation of the multimodal intervention (arm-1) guided by the RE-AIM and CFIR frameworks using in-depth interviews among 3 stakeholder groups: (1) frontline providers (n=10); (2) administrators (n=10); and (3) a subset of the Black and Latinx PWUO from the multimodal intervention arm-1 (n=30); and (3) Identify the resources and estimate the associated cost of implementing and sustaining the multimodal intervention and incorporate this information into a customizable budget-impact tool and conduct a comprehensive economic evaluation to calculate the relative economic value (e.g., cost-per quality-adjusted life years, cost-per OUD treatment days) of each study arm from the healthcare sector, state- policymaker, and societal perspectives which will also inform implementation framed by RE-AIM. Our team is poised to conduct this study given expertise in novel Cultural & Structural Humility Training designed for peers, in open source AI-driven mobile health innovations...