Research demonstrating the positive effects of Mindfulness-Based Interventions (MBIs) has led to a growing interest in the use of mindfulness across a range of populations and psychological difficulties. This thesis explores the feasibility and benefits of mindfulness in relation to self-esteem and psychosis. Paper one is a systematic review exploring the relationship between mindfulness and self-esteem. The review had two main aims: to synthesise and critically appraise studies exploring the association between mindfulness and self-esteem, and studies investigating the impact of MBIs on self-esteem. Thirty-two studies were identified and quality assessed to guide interpretation of results. All cross-sectional studies found significant positive correlations between dispositional mindfulness and self-esteem, whilst improvements in self-esteem were found in the majority of MBI studies. Despite largely positive findings, the review highlighted the need to interpret these with caution due to methodological weaknesses. Priorities for research were identified, with further investigations needed to assess the impact of mindfulness as an intervention for low self-esteem. Paper two is an empirical paper investigating the feasibility of Mindfulness-Based Cognitive Therapy (MBCT) for psychosis. Sixteen participants, with experience of psychosis, completed an 8-week MBCT group. A repeated measures design was used to explore psychological wellbeing and clinical outcomes following MBCT, including clinical functioning, mindfulness, psychotic symptoms, recovery, beliefs about self, others and voices; and to provide a preliminary exploration of changes in the way a person construes their self, others and their experience of psychosis, following MBCT, using repertory grids. Findings from this feasibility and pilot study were promising, indicating that MBCT groups for psychosis are feasible. Preliminary outcome data highlighted potential areas of change for further investigation in a large scale controlled trial, with possible improvements in participants’ self-reported ability to act with awareness and in recovery, and with some evidence of changes in construing following MBCT. The study demonstrated the feasibility and potential benefits of MBCT groups for people experiencing psychosis, and provided a platform for future research. Paper three is a critical reflection of the papers presented and the research process as a whole. Areas of strengths and weaknesses are highlighted, with an evaluation of the decisions made throughout. The implications for clinical practice are discussed as well as areas for further research.