This review analyzes what is known about how children's judgments of their intellectual competence and their definition and criteria for evaluating competence change with age and experience in achievement contexts. Research documenting an age-related decline in children's average ratings of their intellectual ability is interpreted in terms of developmental changes in children's concept of ability and the criteria they use to evaluate ability. The studies reviewed suggest that children's concept of ability becomes more differentiated with age and that children do not develop a concept of ability as a stable trait until late in elementary school. Research also indicates that the criteria children use to assess intellectual competence shift over the elementary school years--from effort, social reinforcement, and mastery to objective and normative information.