Using different comparison groups than in earlier work, we find that ability tracking in math classes has little effect on growth in student math achievement. Previous articles use dummy variables to compare students from classes of high, middle and low ability to the average heterogeneously...

This chapter summarizes the recent literature on peer effects in student outcomes at the elementary, secondary, and post-secondary levels. Linear-in-means models find modest sized and statistically significant peer effects in test scores. But the linear-in-means model masks considerable...

Studying with higher ability peers increases student performance, yet we have little idea why. We exploit random assignment of students to classrooms and find positive peer effects on test scores. With rich data on nineteen potential mechanisms, we then estimate how effects on attitudes,...

Studying with higher ability peers increases student performance, yet we have little idea why. We exploit random assignment of students to classrooms and find positive peer effects on test scores. With very rich data on seventeen potential mechanisms, we then estimate how peer effects on...

This study uses sociometric data to show that social connections in the classroom shape the diffusion of the negative externalities on cognitive achievement generated by abused and neglected peers. We find the strongest negative effects for students who are socially closest to the abused and...