The Endorsement for Culturally Sensitive, Relationship-Focused Practice Promoting Infant Mental Health® (Endorsement®) recognizes knowledge, skills, and reflective experiences that promote quality service when working with or on behalf of infants, toddlers, and families. Developed by the Michigan Association for Infant Mental Health, the Endorsement is licensed for use in 27 states and Western Australia, providing critical support for the promotion of infant mental health (IMH) across disciplines and at multiple levels of service. This article examines how four states have used the Endorsement to increase services for infants, very young children, and their families, and to improve quality of care.