Summarizes evidence for the effects of class-size reduction from experimental and nonexperimental measurements, addresses questions about the robustness of each type of estimate, and suggests hypotheses that could reconcile differences resulting from conflicting evidence. Discusses potential costs and the implications for future research into the…

Literature on the relation between class size and student achievement is reviewed, and policy alternatives are suggested. Class size reduction strategies, focusing on individual or small group tutoring, are proposed for primary and secondary instruction. Implementing these strategies requires ambitious staff development programs. (SLD)

Although experimental results indicate that smaller classes promote higher achievement in early elementary school, the broader literature on class-size effects is inconclusive. This seeming contradiction raises questions about the generalizability of experimental evidence, an issue that this article addresses by examining the effects of class size…