Background. There have been recent advances in the ability to identify people at high risk of developing psychosis. This has led to interest in the possibility of preventing the development of psychosis and provides the opportunity to investigate psychological mechanisms that may confer vulnerability to psychosis.Method. Fifty-eight patients at ultra-high risk of developing a first episode of psychosis were compared with 56 non-patients matched for age and occupational status on measures of meta-cognition, schizotypal traits, dysfunctional attitudes and distress.Results. Analyses of covariance revealed that people at high risk of developing psychosis scored higher on measures of cognitive vulnerability, including negative meta-cognitive beliefs, beliefs about rejection and criticism from others, and discrepancies in self-perception, schizotypal traits and general mental distress. Correlational analyses revealed that negative meta-cognitive beliefs, dysfunctional attitudes and beliefs about rejection and criticism from others were positively associated with several dimensions of symptomatology in at-risk mental states (ARMS) patients.Conclusions. Cognitive and personality factors appear to characterize people at high-risk of developing psychosis and are associated with their distressing experiences. The clinical implications of these findings are discussed.