His best known works include: reviews of the research on long - term effects; benefit - cost analyses of the Perry Preschool and Abecedarian programs; randomized
trials comparing alternative approaches to educating children including length of day, monolingual versus dual - language
immersion, the Tools of the Mind curriculum; and, the series of State Preschool Yearbooks providing annual state -
by - state analyses of progress in public pre-K.