The Persistence of Early Childhood Maturity: International Evidence of Long-Run Age Effects*

A continuum of ages exists at school entry due to the use of a single school cutoff date—making the “oldest” children approximately 20 percent older than the “youngest” children. We provide substantial evidence that these initial maturity differences have long-lasting effects on student performance across OECD countries. In particular, the youngest members of each cohort score 4–12 percentiles lower than the oldest members in grade four and 2–9 percentiles lower in grade eight. In fact, data from Canada and the United States show that the youngest members of each cohort are even less likely to attend university.