Twenty-four 3.5-year-old children who initially showed poor performance on false-belief tasks participated in a training protocol designed to promote performance on these tasks. Our aim was to determine whether the extent to which children benefited from training was predicted by their performance on a battery of executive functioning tasks. Findings indicated that individual differences in executive functioning performance strongly and consistently predicted improvement in children's false-belief performance and their ability to appropriately explain false-belief-based behavior, both during the training period and during the posttest. These findings were robust after statistically controlling for several relevant covariates. These results are consistent with the suggestion that executive functioning skills promote developments in theory of mind by facilitating the ability to reflect upon and learn from relevant experience.