This study proposes a novel way of modeling the heterogeneous effects of schooling based on the notion that learning is maximized when the skill of the child matches the complexity of the learning experiences at school. It offers direct evidence about the importance of this match using longitudinal information on test scores and schooling attained by children from Peru, India, and Vietnam. Using data from Peru, it also finds that the relation between the effect of schooling and early childhood skill can follow an inverted-U shape. Increasing early childhood skill will raise the productivity of the school up to the point where it matches school complexity. Further increases in child skill, however, will reduce the productivity of schooling as they will widen the mismatch. If one relates the quality of schools to the amount of learning they produce, this framework predicts that quality gains can be achieved by reducing these mismatches.