One-hundred-six 5-year-olds' (M[subscript age] = 5;6; SD = 0.40) were trained with second-order false belief tasks in one of the following conditions: (a) "feedback with explanation"; (b) "feedback without explanation"; (c) "no feedback"; (d) "active control." The results showed that there were significant improvements in children's scores from pretest to posttest in the three experimental conditions even when children's age, verbal abilities, or working memory scores were controlled for. The training effect was stable at a follow-up session 4 months after the pretest. Overall, our results suggest that 5-year-olds' failures in second-order false belief tasks are due to lack of experience and that they can be helped over the threshold by exposure to many stories involving second-order false belief reasoning, including why questions.