Colorectal cancer (CRC) is the second highest cancer killer worldwide. Owing to the nature of CRC, especially the potential to detect pre-disease abnormalities that subsequently reduces the incidence, morbidity, and mortality of the disease, it is one of the few cancers for which population screening is recommended. Despite this, population CRC screening programs demonstrate poor uptake. For example, the Australian National Bowel Cancer Screening Program has a 43.5% participation rate in screening, and 62% completion rate in follow-up colonoscopy. Both rates are lower than desired, and representative of uptake globally, and are therefore of interest for health behaviour research. Much of the existing literature has focused on the influence of cognitions in CRC screening deterrence (e.g., Health Belief Model). However, more recently literature has begun to investigate the role of emotions in health behaviours to address some of the previous literature limitations. Hence, the general purpose of the studies described in this thesis was to investigate the role of aversive emotions in CRC screening. Four studies were conducted to address three research aims, with data collection from four samples of community members, relevant to the existing target populations of CRC screening. These aims were founded on limitations of the exiting literature (i.e., limited emotion targeted research and available comprehensive measures specific to CRC screening). The first aim was to investigate the role of disgust (i.e., trait and state measures). The second aim was to investigate the emotional barriers to CRC screening in community members, with special focus on group differences between screeners, non-screeners, and individuals younger than the targeted age. Finally, the third aim was to develop and psychometrically validate an instrument to measure affective barriers to CRC screening. [...]