High-quality, birth-to-five preschool has demonstrated positive effects on a variety of life outcomes. A new analysis of the Abecedarian preschool program, one of the oldest and most cited U.S. early childhood intervention programs, shows positive effects on adult health. Using recently collected data in a biomedical sweep, this research finds that children who were in the treatment group have significantly better health in their mid-30s. The estimated treatment effects survive corrections for several statistical challenges faced by small-sample randomized controlled trials. The findings show the potential of early life programs to prevent disease and promote adult health. (author abstract)