ICH evaluated Cambridge Health Alliance’s primary care behavioral health integration program, a complex intervention aimed at building capacity to treat mental health conditions and substance use disorders within 12 primary care clinics. ICH collaborated closely with key stakeholders to develop a program logic model and evaluation plan, and implemented a comprehensive mixed-methods evaluation that incorporated quantitative analysis of electronic health record data, provider and staff surveys, qualitative interviews, and time tracking data. The evaluation demonstrated several positive early impacts and allowed CHA to meet Section 1115 Medicaid Waiver reporting requirements. CHA also used the evaluation findings to identify priority areas for ongoing program improvement. ICH is now building on this work to disseminate findings through academic publications and other venues.