The aims of this research were to examine the development of teaching skills in preschool children and to explore the relation between teaching and theory of mind (ToM). After learning a new board game, 3.5-, 4.5-, and 5.5-year-old children (N = 46) were asked to teach a confederate who "doesn't know how to play the game." They also received two ToM tasks. Children's teaching skills increased significantly with age: older children taught longer, explained more rules, used more strategies when teaching, and were more likely to recognize and attempt to correct "errors" committed by the confederate. After being controlled for age, individual differences in ToM were significantly correlated with the number of strategies used when teaching. This research suggests that a dynamic teaching task is sensitive to developmental changes and that aspects of children's teaching may serve as a window into their developing understanding of mental states.