The economics of class size

Class-size reduction is a politically popular but relatively expensive education reform. Understanding the causal relationship between class size and student achievement is critical for determining whether class-size reduction can be recommended as a policy to improve student outcomes. We begin with a review of the theory of why class size might matter, followed by a discussion of the empirical strategies for identifying the causal impact of class size on student achievement. Next, the empirical literature on class-size reduction is reviewed, focusing on studies using experimental and quasi-experimental techniques because these rely on the most credible strategies for identifying the true causal relationship between class size and student achievement.