Perinatal depression affects between 12% and 20% of pregnant and postpartum women and is underdiagnosed. The American College of Obstetricians and Gynecologists and the U.S. Preventive Services Task Force recently recommended universal perinatal depression screening. We discuss challenges to instituting universal screening, describe the development and implementation between 2007 and 2014 of Kaiser Permanente Northern California's successful program, and highlight key measures of success. A quality improvement system approach with four steps guided development: 1) identify and use best practices, 2) identify champions and educate clinicians, 3) use data that drive performance, and 4) streamline office workflow. Clinical success was determined by at least 50% improvement in depression care metrics from diagnosis to 120 days afterward. Depression diagnoses, Patient Health Questionnaire-9 scores, medication dispensation, and treatment for all births in 2014 (N=37,660) were extracted from electronic health records. Ninety-six percent of pregnant and postpartum women were screened at least once. Fourteen percent screened positive for depression (Patient Health Questionnaire-9 score of 10 or greater). Approximately 6% of pregnant and postpartum women had severe depression with a Patient Health Questionnaire-9 of 15 or greater and a depression diagnosis, and 80% of these women received treatment. Forty percent of women with a depression diagnosis demonstrated improved symptoms. Kaiser Permanente Northern California's universal perinatal depression screening program can serve as a model for the feasibility and clinical effectiveness of universal depression screening in obstetric care.