We study the effects of peers on school achievement, with detailed data on children making the same primary to secondary school transition in consecutive years in England. Our estimates show that secondary school composition, on entry at age 12, affects achievement at age 14, although the effect...

We study the effects of peers on school achievement, with detailed data on children making the same primary to secondary school transition in consecutive years in England. Our estimates show that secondary school composition, on entry at age 12, affects achievement at age 14, although the effect...

We show that in school systems with grade retention or redshirting, birth cohort size is negatively related to the grade-level share of students who are too old for their grade. This compositional effect gives rise to an upward bias in estimates of class size effects based on commonly used...