This longitudinal study examined the concurrent and predictive relations between executive function (EF) and theory of mind (ToM) in 82 preschoolers who were assessed when they were 2, 3, and 4 years old. The results showed that the concurrent relation between EF and ToM, after controlling for age, verbal ability, and sex, was significant at 3 and 4 years of age but not at 2 years of age. Hierarchical regression analyses showed that EF at age 2 significantly predicted ToM at age 3 and that EF at age 3 significantly predicted ToM at age 4, over and above the effects of age, verbal ability, and prior performance on ToM tasks. However, ToM at ages 2 and 3 did not explain a significant amount of variance in EF at age 4. Bootstrap procedures revealed that verbal ability at age 3 fully mediated the relation between ToM at age 2 and EF at age 4. (Contains 1 figure and 10 tables.)