Three studies examined the effects of context on decisions about the reality status of novel entities. In Experiment 1 (144, 3- to 5-year-olds), participants less often claimed that novel entities were real when they were introduced in a fantastical than in a scientific context. Experiment 2 (61, 4- to 5-year-olds) revealed that defining novel entities with reference to scientific entities had a stronger effect on reality status judgments than did hearing scientifically oriented stories before encountering the novel entities. The results from Experiment 3 (192, 3- to 6-year-olds) indicated that definitions that support inferences facilitate reality status judgments more than do definitions that simply associate novel and familiar entities. These findings demonstrate that children share with adults an important means of assessing reality status.