This study examines the gendered effects of early and sustained exposure to high-performing peers on female educational trajectories. Exploiting random allocation to classrooms within middle schools, we measure the effect of male and female high performers on girls' high school placement...

This article relies on a large-scale field experiment in Mexico to measure the effects of two ability-grouping models (tracking and heterogeneous/bimodal groups) on student learning outcomes during middle school. Both strategies yielded an average learning gain of 0.08 of a standard deviation....