The federal government, through SAMHSA?s Opioid State Targeted Response (Opioid-STR) grants, has provided funding to each state to ramp up the range of responses in hopes of reversing the ongoing opioid crisis. Pharmacotherapy to address opioid use disorders (OUDs) is an evidence-based practice although it is clearly underutilized, especially by primary care providers. Washington State is implementing a ?Hub & Spoke? (H&S) integrated care model to expand access to pharmacotherapy services (also known as medicationassisted treatment or MAT) and reduce unmet need for people with OUDs regardless of how or where clients enter the treatment system. This proposed R21/R33 study will take a hybrid effectiveness-implementation approach, with both implementation evaluation and effectiveness as primary goals. It is essential to understand how the H&S model is implemented to understand if, how, and why it is an effective approach to treat OUDs. The specific aims for the proposed study are as follows. R21 PHASE ? Early Implementation and Feasibility: (1) Confirm the feasibility of collecting client and program data from hubs, spokes and comparison groups; collect baseline data; and confirm data linkages with other key databases; (2) Finalize elements needed for R33 effectiveness study, including comparison groups, dependent variables, and key analytic subgroups; (3) Assess the early implementation of the H&S model. R33 PHASE ? Effectiveness: (1) Test whether the H&S model is effective for addressing OUDs; (2) Determine whether people with OUDs treated in the H&S model have better outcomes if they receive pharmacotherapy + counseling versus only pharmacotherapy. (3) Test whether the H&S model is differentially effective for subgroups (e.g., age, gender, OUD type, mental disorder, rural); (4) Examine, using mixed methods, implementation of the H&S model and how specific aspects across and within each hub-spoke network relate to the overall effectiveness. This study will focus primarily on adults (18+) with OUDs in Washington who are enrolled in Medicaid, about 90% of people with OUDs in treatment in Washington. Effectiveness measure include a range of structure, outcome and process measures at client- and system-levels, including drug use, overdose, access to pharmacotherapy, and arrests, incarceration and employment. Washington is a leader in addiction treatment services and detailed, linkable data systems. Statistical methods will be used to ensure a rigorous quasiexperimental design. The findings from this study will enable us to understand the essential elements of the H&S model for the most effective treatment for OUDs, and how to bring more primary care providers to the addiction pharmacotherapy practice. It will serve as a model for other states and systems, offering a flexible approach that addresses many existing barriers to the use of pharmacotherapy for people with OUDs, ensuring that there is no wrong door to enter treatment and that people with OUDs receive the treatment with the best success for promoting recovery.