This thesis consists of two sections, the first of which is a systematic review of selfreport measures of mindfulness. The review aims were to evaluate the psychometric properties of each of the identified measures and examine their utility for research and clinical practice. Definitions of mindfulness were central to the differences found between measures, and as such this review also provides an overview of how mindfulness has been conceptualised in the literature. This review has been presented in the format required by the journal, Clinical Psychology Review. The second section is a meta-analysis which examines the efficacy of mindfulnessbased stress reduction (MBSR). Mindfulness-based interventions are increasingly being applied in a range of settings and the evidence base is growing. Specifically, this review aimed to determine the effectiveness of MBSR on quality of life for people suffering from chronic physical health conditions. The methods and results of the meta-analysis are described in detail, followed by a discussion of the findings. A more concise overview is then provided as a journal article, in the format required by the British Journal of Clinical Psychology. The guidelines for submission to both journals are included in Appendix 1 and 2 respectively.