Firefly is a patient-centered service-delivery model that aims to improve the quality of care and reduce costs for pregnant and postpartum women with opioid use disorder (OUD) and their infants through state-driven care transformation. Firefly is partnership between TennCare and the Vanderbilt University Medical Center, funded by the Center for Medicare and Medicaid Innovation (CMMI) Maternal Opioid Misuse (MOM) model. Firefly will begin accepting patients on July 1, 2021.