Summarizes research findings on a Tennessee experiment in small classes for primary grades--Project STAR (Student/Teacher Achievement Ratio)--and on similar projects in other states. Discusses effects on student achievement and classroom discipline, effects of small classes versus larger classes with teacher aide, costs, long-term impacts, and…

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…