Objectives. Coeliac disease (CD) is an autoimmune condition managed by a lifelong therapeutic gluten-free diet. Previous research suggests that the chronicity of CD, the limitations imposed by the gluten-free diet, and the risk of other associated diseases can have a negative impact on health-related quality of life (HRQoL) and psychological well-being. The aim of this study was to explore the illness perceptions and self-efficacy beliefs of adults with CD in the United Kingdom and to report their subjective levels of HRQoL and psychological well-being. Design. The study employed a cross-sectional postal questionnaire design. Method. Participants (n= 288) were adults with CD recruited via Coeliac UK. Measures of well-being, HRQoL, self-efficacy, illness perceptions, and dietary self-management were analysed. Preliminary descriptive and univariate procedures were employed before bivariate tests of association or difference were carried out. Backward stepwise multiple regression analysis was used to investigate the predictive strength of variables on well-being, quality of life, and self-efficacy. Logistic regression was used to look at the influence of variables on adherence. Results. Results indicate that HRQoL and psychological well-being were comparable to those found in previous related studies. Participants with weak beliefs in the serious consequences of CD and poorer emotional reactions to the condition had a greater likelihood of having enhanced HRQoL, improved psychological well-being, and higher self-efficacy. Strong beliefs in personal control and a greater perceived understanding of CD were associated with greater self-efficacy. Conclusions. Perceived self-efficacy and illness perceptions could play a role in informing psychological interventions for individuals with CD.