Background Collaborative care is an evidence-based multidisciplinary model shown to improve patient depression and anxiety outcomes. Although there is robust literature showing the effectiveness of collaborative care on depression and anxiety symptoms, there is little published on outcomes of collaborative care implementation or the efficacy of collaborative care compared with psychiatric referrals. Reported here is a study protocol examining a novel depression and anxiety collaborative care program in a large, integrated health care system. Methods This is a mixed methods study of the Achieving Depression and Anxiety Patient-Centered Treatment (ADAPT) program as compared to outpatient psychiatric care at Kaiser Permanente Northern California, a large, integrated health care delivery system. The ADAPT program was designed using collaborative care principles, including measurement-based care, accurate diagnosis, and population management. Eligible participants will be ≥ 18 years old with mild to moderate-severe depressive symptoms as measured by the Patient Health Questionnaire-9. Exclusion criteria include acute suicide risk and serious mental health comorbidities. Implementation is examined using the reach, effectiveness, adoption, implementation, and maintenance (RE-AIM) framework and interviews with program stakeholders. Results Pending. Conclusion Study data will help inform future collaborative care efforts while expanding the literature base. The Achieving Depression and Anxiety Patient-Centered Treatment program may improve patient outcomes and access to quality depression and/or anxiety care.