The Preschool Development Grant B-5 (PDG B-5) efforts have been grounded in an intentional interagency, inter-program, cross-secretariat collaboration of early childhood education and care programs and services. The Mixed Delivery System for children birth to five includes a wide array of programs and services funded and administered by federal, state, local and community-based organizations. The PDG B5 work focused on a subset of those programs- only those that are managed at the state level and whose primary purpose is supporting families in the broader developmental health and the optimal cognitive and social emotional development of their children. This “PDG B-5 Mixed Delivery System” includes programs and services overseen by the Executive Office of Education (EOE) and the Executive Office of Health and Human Services (EOHHS), as well as four of their respective agencies: At EOE, the Department of Early Education and Care (EEC), the Department of Elementary and Secondary Education (DESE), and the Children’s Trust (CT); and, at EOHHS, the Department of Public Health (DPH). (author abstract)