What Have Researchers Learned from Project STAR?

Project STAR (Student/Teacher Achievement Ratio) was a large-scale randomized trial of reduced class sizes in kindergarten through the third grade. Because of the scope of the experiment, it has been used in many policy discussions. For example, the California statewide class-size-reduction policy was justified, in part, by the successes of Project STAR. Recent (failed) proposals in the Senate that sought federal assistance for class-size reductions were motivated by Project STAR research. Even the recent discussion of small schools often conflates the notion of small schools and smaller classrooms.

Because of the importance of Project STAR, it has been studied by many scholars looking at a wide variety of outcomes and even exploiting the randomization to understand variations in inputs and other aspects of the education production function that do not directly relate to class size. This paper provides an overview of the academic literature using the Project STAR experiment.