Since 1975, the Chicago public schools have been conducting ongoing research and development related to the identification and remediation of prekindergarten children with potential learning problems. The present study describes initial efforts toward the creation of a longitudinal data base aimed at determining (1) prekindergarten-age characteristics related to later school achievement, and (2) predictive validity of the Chicago EARLY Assessment. The study reports details of the follow-up of the original EARLY sample and reliability data on the EARLY Assessment. The authors strongly argue the importance of conducting longitudinal research in the public schools. (Author)