Objective To examine the influence of Oregon's coordinated care organizations (CCOs) and pay‐for‐performance incentive model on completion of screening and brief intervention (SBI) and utilization of substance use disorder (SUD) treatment services. Data Sources/Study Setting Secondary analysis of Medicaid encounter data from 2012 to 2015 and semiannual qualitative interviews with stakeholders in CCOs. Study Design Longitudinal mixed‐methods design with simultaneous data collection with equal importance. Data Collection/Extraction Methods Qualitative interviews were recorded, transcribed, and coded in ATLAS.ti. Quantitative data included Medicaid encounters 30 months prior to CCO implementation, a 6‐month transition period, and 30 months following CCO implementation. Data were aggregated by half‐year with analyses restricted to Medicaid recipients 18–64 years of age enrolled in a CCO, not eligible for Medicare coverage or Medicaid expansion. Principal Findings Quantitative analysis documented a significant increase in SBI rates coinciding with CCO implementation (0.1 to 4.6 percent). Completed SBI was not associated with increased initiation in treatment for SUD diagnoses. Qualitative analysis highlighted importance of aligning incentives, workflow redesign, and leadership to facilitate statewide SBI. Conclusions Results provide modest support for use of a performance metric to expand SBI in primary care. Future research should examine health reform efforts that increase initiation and engagement in SUD treatment.