Four-year-olds' an adults' inferences based on shared conceptual properties, category labels, and perceptual information were assessed in 4 experiments. Stimuli included novel animals (Studies 1, 3, and 4) and familiar animals (Study 2). The experiments suggest that both category membership information and similarity (in the form of conceptual information and perceptually provided information) affect inferences. Furthermore, conceptual attribute information and category membership information were used differently by adults but not by children. It is concluded that both children's and adults' inferential behavior is influenced by perceptual information, conceptual attribute information, and category membership information, as well as by hypotheses about how these kinds of information relate.