How do children acquire humankind's remarkable cognitive skills? Why are the abilities children acquire readily, such as native-language fluency, harder for adults? Although attitudes to these questions span the continuum from nativism to learning theory, answers remain elusive. We relate a recent model of language acquisition in childhood to advances in the neuroscience of adult cognitive control, to propose a domain-general shift in the architecture of learning in childhood. The timing of this supports children's imitative, unsupervised learning of social and linguistic conventions before the maturation of cognitive control gives individuals greater self-direction, which causes learning to become less conventionalized and more idiosyncratic. These changes might represent an important adaptation supporting the development and learning of cultural and linguistic conventions.