Among the many models of school reform that have emerged in the late 20th-early 21st centuries, one has endured for more than 50 years: the School Development Program (SDP). Established by child psychiatrist James P. Comer and the Yale Child Study Center, the SDP is grounded in the belief that successful schooling-particularly for children from disadvantaged backgrounds-must focus on the whole child. It encompasses both academics and social-emotional development, and it is founded on positive and productive relationships among students, teachers, school leaders, and parents. It includes six developmental pathways (cognitive, social, psychological, physical, linguistic, and ethical) and explains how its key components create a comprehensive approach to educating children for successful outcomes. Recollections by Comer, school leaders, teachers, and SDP staff show how the challenges and successes that eventually transformed severely underperforming schools into models of excellence.