Background: Delusions are defined as false beliefs different from those that almost everyone else believes. The aim was to develop a new measure (the Cardiff Beliefs Questionnaire, CBQ) to establish the range and prevalence of delusion-like beliefs (DLB) and compare these to other types of beliefs in the general population. Sampling and Methods: A total of 1,000 participants completed the CBQ, which uniquely assesses a broader range of currently held beliefs [delusion-like (bizarre and non-bizarre), paranormal and religious and general political/social beliefs) using this large stratified sample. Results: Strong belief in 1 or more DLB was reported by 39% of the participants (91% reporting ‘weak’, ‘moderate’ or ‘strong’ belief in at least 1 DLB). Moreover, 25% endorsed at least 1 bizarre DLB (76% one or more at any strength). Endorsements of DLB were strongly correlated with paranormal and religious beliefs but not general political/social beliefs. Conclusions: Both bizarre and non-bizarre DLB are frequently found in the general population, lending support to the psychosis continuum account and need to revise key clinical criteria used to diagnose delusions. The good psychometric properties demonstrated by the CBQ indicate that this measure is a useful tool to investigate the wider continuum of beliefs held in the general population.