We investigate the effect of peer group composition on language improvement in language classes for adults. Using unique survey data of migrants participating in an intensive language course in Germany, we find that the age and skill composition of groups affect skill acquisition as assessed by...

Using longitudinal elementary school teacher and student data, we document that students have larger test score gains when their teachers experience improvements in the observable characteristics of their colleagues. Using within-school and within-teacher variation, we further show that a...

Using longitudinal elementary school teacher and student data, we document that students have larger test score gains when their teachers experience improvements in the observable characteristics of their colleagues. Using within-school and within-teacher variation, we further show that a...