Paper One is a systematic review and meta-analysis of the effectiveness of psychological interventions on psychological, quality of life (QOL) and medical outcomes in Inflammatory Bowel Disease. It also aimed to see which, if any, therapeutic modality was more effective. Twenty-eight papers representing twenty-four studies that used a randomised control trial methodology were identified and included in the review. Results showed psychological interventions did not significantly affect psychological or medical outcomes at short-term or long-term follow-up. There was some evidence it increased QOL post-intervention, but this was non-significant at follow-up. Although there was a trend for cognitive interventions to be more effective for psychological and QOL outcomes, all sub-group analyses were non-significant for therapeutic modality. More powerful studies may have detected an effect. The strengths and limitations of the literature are considered with recommendations for future research. Paper Two is an empirical paper conducted with people diagnosed with severe Gastro-Intestinal Dysmotility (GID). It aimed to explore patients' experiences from symptom onset and the process of seeking and receiving a diagnosis. A qualitative exploratory design with semi-structured in-depth interviews was used. Data was analysed using thematic analysis. The distressing experience of GID symptoms are compounded by a delay in validating symptoms and lack of coherent understanding. More knowledge of GID is needed by health professionals to speed up diagnosis and offer more coherent information. The psychological impact of a GID diagnosis should be acknowledged early to help facilitate adjustment. Clinical implications and recommendations for future research are discussed. Paper Three is a critical reflection of the submitted papers and a discussion of the strengths, limitations and methodological decisions considered by the author. In summary, although there is little evidence for the effectiveness of psychological intervention in one population of chronic gastro-intestinal disorders (Paper One), Paper Two demonstrates that receiving a diagnosis of a condition with an intensive medication regime and symptomology has an impact on social life, relationships, and mental health. More research needs to explore the epidemiology of mental health issues in this population and what type of psychological interventions are effective through more controlled trials with larger sample sizes.