Theory of mind (ToM) deficits are central to autistic spectrum disorders, including Asperger syndrome. Research in psychotic disorders has developed a cognitive model of paranoid delusions involving abnormal causal attributions for negative events. Possible aetiologies of these include deficits in social reasoning, specifically ToM. The present study investigated this attributional model of paranoia in Asperger syndrome. Participants diagnosed with Asperger syndrome scored significantly higher on a measure of paranoia and lower on a measure of ToM, compared with the control group. They did not differ in self-concept and causal attributions, contrary to the attributional model of paranoia. A regression analysis highlighted private self-consciousness as the only predictor of paranoia. The theoretical and clinical implications of these findings are discussed.