Currently, medications are the most widely used treatment for IBS (Ford et al., 2009; Ford et al., 2014). Although there is good evidence for the effectiveness of medications in reducing IBS symptomatology and improving quality of life, these medications are also often associated with unpleasant side effects. As a result, there is a growing interest in the utilization of psychological treatments, including cognitive behaviour therapy, for IBS. Cognitive behaviour therapy is a psychotherapeutic approach that addresses maladaptive cognitive processes and behaviours in a systematic, explicit fashion. Although there is good evidence for the effectiveness of cognitive behaviour therapy for the treatment of IBS (Ford et al., 2009; Ford et al., 2014), there is a lack of research examining the mechanisms through which cognitive behaviour therapy influences symptoms of IBS.