Phase 1: The Head Start REDI project began in 2002 with a randomized trial of curriculum and professional development components designed to enhance the impact of Head Start on child school readiness. Two domains of school readiness were targeted: 1) language development/emergent literacy skills, and 2) social-emotional competencies. The program produced improvements in teaching quality in REDI classrooms, including enhanced teacher language use, instructional support, and emotion coaching. Children who received REDI showed enhanced outcomes on measures of vocabulary, emergent literacy skills, social competence, and learning engagement, and reduced aggression at the end of the Head Start year. Sustained benefits were documented in kindergarten.