Two experiments examined how 5- and 10-year-olds revised their category representations when exposed to exemplars that were congruent or incongruent with existing knowledge. Findings indicated that judgments about feature co-occurrent within the learned category were influenced by both stereotypical beliefs and exemplar observation. Stereotypical beliefs had a greater influence on co-occurrent judgments in the knowledge-subtyping than in standard conditions. Effects generalized to judgments about features not presented during training. (Author/KB)