Project summary/abstract State Medicaid programs play a critical role in financing pharmacologic and non-pharmacologic treatments for opioid use disorder (OUD) as they provide coverage for 4 in 10 individuals with OUD. Efforts to improve access to high-quality OUD treatment in Medicaid have been hampered by inconsistent and incomplete measurement of quality and outcomes. States are currently taking myriad approaches to addressing the opioid crisis by changing the way they regulate providers, pay for care, and cover evidence-based treatments in Medicaid. However, there exists no analytic infrastructure for learning about the impact of state policy experimentation on OUD treatment and outcomes as states have no mechanism for sharing data or measurement tools. To overcome these challenges, we harness a Medicaid Distributed Research Network based on academic-state partnerships in Kentucky, Maryland, Michigan, North Carolina, Ohio, Pennsylvania, Virginia, West Virginia, and Wisconsin. These states account for 15 million (20% of) Medicaid enrollees, and the partnerships have access to complete and recent Medicaid data. The objectives of this application are to provide a comprehensive assessment of OUD treatment quality and outcomes in Medicaid, and to inform policy decisions on coverage and payment for evidence-based OUD treatments in Medicaid. First, we will construct and report on 15 standardized measures of OUD treatment performance in the 9 states. Second, we will link Medicaid claims to vital statistics to examine the association between the quality of OUD treatment (e.g., adequate initiation, continuity, follow-up, monitoring, receipt of psychosocial care, screening) and fatal and non-fatal drug overdoses. Third, using quasi-experimental study designs, we will examine associations between Medicaid coverage policies, OUD treatment quality and overdose outcomes. We focus on policy changes implemented recently to expand Medicaid coverage of and reduce barriers to pharmacologic treatment for OUD and to expand payment for residential treatment. Our network is uniquely positioned to disseminate our findings to state policy makers who can act on them. Our network is scalable. We will employ a robust dissemination strategy to distribute the analytic tools we develop to other states. Finally, our network is portable and can be harnessed to address not only the opioid crisis but future drug epidemics facing the US.