Kindergarten, second, fifth, and eighth graders from Germany and the United States participated in structured interviews concerning their beliefs about the nature of intelligence. In both countries, older children were more likely than younger children to link intelligence exclusively to cognitive (rather than noncognitive) abilities, to project an inverse relationship between ability and effort expenditure on academic tasks, and to view intelligence as fixed. U.S. children, in contrast to Germans, were more likely to believe that smart children work harder than children who are less smart, and to argue that intelligence is malleable. Results are discussed in terms of cultural/contextual influences on the development of children's naive theories about intelligence and implications for educational policy.