Attention allocation in word learning may vary developmentally based on the novelty of the object. It has been suggested that children differentially learn verbs based on the novelty of the agent, but adults do not because they automatically infer the object's category and thus treat it like a familiar object. The current research examined whether adults and children differentially learn words or attend to objects without access to category knowledge in a relatively difficult (Experiment 1, adult n?=?54, child n?=?66) and a relatively easy task (Experiment 2, adult n?=?88, child n?=?62). Results show that category knowledge affects noun and verb extension for children but not adults and that adults similarly attended to objects when learning a verb regardless of category knowledge. These findings highlight the importance of investigating how word class, attention allocation, and categorical inference interact across development.