Perinatal psychiatry access programs offer a scalable approach to building the capacity of perinatal professionals to identify, assess, and treat mental health conditions. Little is known about access programs' implementation and the relative merits of differing approaches. We conducted surveys and semistructured interviews with access program staff and reviewed policy and procedure documents from the fifteen access programs that had been implemented in the United States as of March 2021, when the study was conducted. Since then, the number of access programs has grown to thirty state, regional, or national programs. Access programs implemented up to five program components, including telephone consultation with a perinatal psychiatry expert, one-time patient-facing consultation with a perinatal psychiatry expert, resource and referral to perinatal professionals or patients, trainings for perinatal professionals, and practice-level technical assistance. Characterizing population-based intervention models, such as perinatal psychiatry access programs, that address perinatal mental health conditions is a needed step toward evaluating and improving programs' implementation, reach, and effectiveness.