We describe the development, implementation, and evaluation of a comprehensive preschool to third grade prevention program for the goals of sustaining services at a large scale. The Midwest Child-Parent Center (CPC) Expansion is a multilevel collaborative school reform model designed to improve school achievement and parental involvement from ages 3 to 9. By increasing the dosage, coordination, and comprehensiveness of services, the program is expected to enhance the transition to school and promote more enduring effects on well-being in multiple domains. We review and evaluate evidence from two longitudinal studies (Midwest CPC, 2012 to present; Chicago Longitudinal Study, 1983 to present) and four implementation examples of how the guiding principles of shared ownership, committed resources, and progress monitoring for improvement can promote effectiveness. The implementation system of partners and further expansion using "Pay for Success" financing shows the feasibility of scaling the program while continuing to improve effectiveness. (author abstract)