Modern theories explain children’s cognitive development mainly in term of Bayesian learning (with some innate priors in infancy). But learning cannot be the whole story or else children could learn anything at any age - which they cannot. They cannot because their capacities to experience and cognitively represent the world are structured by the human species’ evolved psychological architecture - inherited from ancient animal ancestors - and this architecture changes in significant ways over the first years of life. The main organizing principle is agency, including shared agency. The developmental proposal is that young infants (below 9 months) are goal-directed agents who cognitively represent and learn about actualities; toddlers are intentional agents who executively represent and learn also about causal, intentional, and logical possibilities; and preschoolers (over 3 years) are metacognitive agents who metacognitively represent and learn also about normative necessities. This agency-based model of cognitive development recognizes the important role of learning, but at the same time places it in the context of the overall agentive organization of children at particular developmental periods.