This study examined the sustained effects of the Head Start Research-based Developmentally Informed (REDI) program, which enriched preschools with evidence-based programming targeting social-emotional and language/emergent literacy skills. 44 Head Start classrooms were randomly assigned to intervention or a usual practice control group, and 356 4-year-olds (25% African American, 17% Latino, 54% female) were followed through the end of 5th grade. Growth curve analyses revealed that significant intervention effects on teacher-rated social adjustment, academic engagement, and parent involvement identified at the end of the Head Start year were sustained throughout elementary school. (author abstract)