In the last 10 years a consensus has developed that the symptoms of psychosis may be better understood by linking the steps between the phenomenological experiences and social, psychological and neurobiological levels of explanation. Cognitive models of psychosis are an important link in this chain. They provide a psychological description of the phenomena from which hypotheses concerning causal processes can be derived and tested; social, individual, and neurobiological factors can then be integrated via their impact on these cognitive processes. In this paper, we set out the cognitive processes that we think lead to the formation and maintenance of the positive symptoms of psychosis and we attempt to integrate into our model research in social factors. If this model proves useful, a fuller integration with the findings of biological research will be required (Frith, 1992).