Four- to 9-year-olds and adults (N = 256) viewed a series of pictures that were covered with occluders to reveal nondescript or identifiable parts. Participants predicted how 3 characters, 1 who had previously viewed the full picture and 2 who had not, would interpret the obstructed drawings. Results showed significant development between 4 and 9 years and between 9 years and adulthood in understanding thought diversity as well as situations in which people should think alike. There was also evidence for a U-shaped developmental curve, with 6- to 7-year-olds most often overextending the rule that people will think differently, particularly on the initial testing trials. Performance on the different interpretive theory-of-mind measures was differentially related to individual differences in inhibitory control and verbal working memory.