This study is a randomized control trial of full- versus half-day prekindergarten (pre-K) in a school district near Denver, Colorado. Four-year-old children were randomly assigned an offer of half-day (4 days/week) or full-day (5 days/week) pre-K that increased class time by 600 hours. The full-day pre-K offer produced substantial, positive…

Demonstrating program impact through documentation of child progress is a problem in programs for handicapped children. It is proposed that intervenors consider approaches closely tied to the actual interventions. Four strategies are described: increased magnitude of intervention, increased power of design, refined assessment procedures, and…