--- - |2+ Aim The Metacognitions Questionnaire‐30 (MCQ‐30) has been used to assess metacognitive beliefs in a range of mental health problems. The aim of this study is to assess the validity of the MCQ‐30 in people at risk for psychosis. Methods One hundred eighty‐five participants meeting criteria for an at risk mental state completed the MCQ‐30 as part of their involvement in a randomized controlled trial. Confirmatory and exploratory factor analyses were conducted to assess factor structure and construct validity. Results Confirmatory factor analyses confirmed the original five‐factor structure of the MCQ‐30. Examination of principal component analysis and parallel analysis outputs also suggested a five‐factor structure. Correlation analyses including measures of depression, social anxiety, and beliefs about paranoia showed evidence of convergent validity. Discriminant validity was supported using the normalizing subscale of the beliefs about paranoia tool. Conclusions The MCQ‐30 demonstrated good fit using the original five‐factor model, acceptable to very good internal consistency of items was evident and clinical usefulness in those at risk for psychosis was demonstrated. - Clinical Psychology & Psychotherapy, Volume 25, Issue 5, Page 710-720, September/October 2018.