In this article, we document gaps in school readiness and achievement in the United States and how they adversely affect the life course development of children and families from underrepresented groups. We emphasize the promising role of preschool-to-3rd grade (P-3) programs to reduce a variety of achievement gaps through comprehensive strategies that enrich educational and family experiences during most of the first decade of life. Implementation of the core elements of effective learning experiences, collaborative leadership, aligned curriculum, parent involvement and engagement, professional development, and continuity and stability in the Child-Parent Center (CPC) Program have shown relatively strong and sustained effects on school achievement, especially for Black children growing up in urban poverty. (author abstract)