Previous studies have revealed a “theory of mind” impairment in children with autism. The aim of this study was to assess whether it is possible to intervene by teaching children with autism to understand the mental states of emotion, belief, or pretence. Results showed that it is possible to teach children with autism to pass tasks that assess emotion and belief understanding. Introducing unfamiliar materials in structurally similar tasks did not adversely influence teaching effects, either immediately after teaching, or 2 months later. However, teaching effects did not generalize to tasks in domains where children received no teaching. In addition, no significant progress in spontaneous pretend play resulted from teaching. These results indicate that children may be passing tasks using rules rather than any genuine understanding of the concepts involved.