During the academic year of 1978-1979, a system for the early identification of students who were likely to have difficulty with the core curriculum in language and/or mathematics was introduced into the London, Canada, system at the kindergarten and grade 1 levels. In the two subsequent years the early identification system was extended to grades 2 and 3. This report briefly outlines the general findings resulting from the identification process and summarizes the results of several studies which have attempted to assess its concurrent and predictive validity. It is suggested that the system is working fairly well and that a satisfactory degree of concurrent and predictive validity exists. (MP)