ObjectiveTo expand a hospital system’s maternal mental health program to standardize screening for perinatal mood and anxiety disorders. DesignQuality improvement initiative using a continuous Plan–Do–Study–Act (PDSA) cycle. Setting/Local ProblemIn a hospital system consisting of 66 maternity care centers across the United States, there was significant variation in maternal mental health screening, referral, and education practices. The COVID-19 pandemic and increasing rates of severe maternal morbidity further elevated system-level concern about the quality of maternal mental health care being provided. ParticipantsPerinatal nurses. MethodsAn “all-or-none” bundle methodology was used to measure adherence to a system standard for maternal mental health screening, referral, and education. InterventionsA toolkit was designed internally to support streamlined implementation and ensure standardization for screening, referral, and education. This comprehensive toolkit includes screening forms, a referral algorithm, staff education, patient education literature, and a community resource list template. Training on how to use the toolkit was provided to nurses, chaplains, and social workers. ResultsThe initial system bundle adherence rate was 76% (2017) in the first year of the program. The following year, the bundle adherence rate increased to 97% (2018). Despite the disruption caused by the COVID-19 pandemic, this mental health initiative has maintained an overall adherence rate of 92% (2020–2022). ConclusionThis nurse-led quality improvement initiative has been successfully implemented across a geographically and demographically diverse hospital system. The initial and sustained high rates of adherence with the system standard for screening, referral, and education illustrate perinatal nurses’ commitment to the delivery of high-quality maternal mental health care in the acute care setting.