This paper continues our earlier investigation of autistic children's deficit in attributing beliefs to others--in their "theory of mind." Three experiments are reported. The first tests the prediction that autistic children will fail to distinguish mental and physical entities. The second tests the prediction that they will also be unaware of the mental function of the brain. The third tests the prediction that they will be unable to take into account their own mental states. This latter prediction was tested using Appearance-Reality (A-R) tasks. All three predictions were supported. Deficits in these areas were not found among mentally handicapped or normal children of the same or lower mental and chronological age, suggesting that they may be autism-specific and independent of general developmental delay. It is argued that autistic children's failure to make A-R distinctions is consistent with Leslie's (1987) metarepresentation theory of autism.