In this paper Cronbach comments on the gap that exists between learning research and curriculum development. Essentially, Cronbach is saying that learning theories have not been particularly helpful in telling the curriculum maker about arranging an optimum sequence of experiences for children in school. Current curriculum reforms are proceeding on other bases. He finds Piaget's theory of cognitive development posing similar questions of bridging the gap between cognitive development and curriculum development, but not emerging with clear pedagogical answers.