Background: The Brief Core Schema Scales (BCSS) were developed to provide a theoretically coherent self-report assessment of schemata concerning self and others in psychosis. They provide a more useful measure of schemata about self and others than traditional measures of self-esteem. Aims: The aim of this study was to determine if these scales would be useful in a sample of individuals who are at clinical high risk of psychosis to help identify targets for intervention. Method: Thirty-eight individuals who are at high risk for psychosis were administered the Scale of Prodromal Symptoms, the Calgary Depression Scale, the Brief Core Schema Scales and the Young Schema Questionnaire–short version. Results: Results suggested that these scales are appropriate for this population and that negative evaluations of the self and others were significantly associated with attenuated psychotic symptoms and, in particular, suspiciousness.