This thesis forms part of the examination for the degree of Doctor of Clinical Psychology (ClinPsyD) in the Faculty of Biological Medicine and Health at the University of Manchester. The thesis has been written by Kate Murphy and submitted in October 2018 for examination in November 2018. The thesis focuses on the effectiveness of psychological interventions for treating self-harm, suicide attempts, thoughts and behaviour in people experiencing/diagnosed with borderline personality disorder. The thesis also reports on an investigation of the association between basic emotions in suicide ideation and suicide potential, beyond that already explained by known clinical risk factors such as hopelessness and depression.1 Paper 1 provides a comprehensive systematic review and meta-analysis of the available research on the effectiveness of psychological interventions for suicide prevention in borderline personality disorder. The review aimed to evaluate the effectiveness of psychological interventions in reducing the frequency of self-harm, suicide attempts and severity of suicidal thoughts and behaviour over time. It also set out to determine which interventions were the most effective in reducing suicide risk. The evidence so far suggests that dialectical behaviour therapy is effective for treating self- harm, suicide attempts, suicide ideation in borderline personality disorder and that these benefits are likely to be maintained over 12 months. However, the non-significant gains from other types of interventions such as cognitive and behavioural approaches, psychodynamic psychotherapies and organisational interventions might simply reflect the small number of trials conducted among a small number of participants. It is likely that larger trials would show benefits. Therefore, further research is needed in order to provide solid evidence of effectiveness, cost-effectiveness and implementation potential. Paper 2 describes an investigation into the role of basic emotions in suicide ideation and suicide potential. A total of 101 participants from mental health inpatient and community services completed study questionnaires. The results indicated that suicide ideation and suicide potential presented with different emotional profiles. Emotions such as anger, disgust and fear seemed more relevant to suicide potential, whilst sadness appeared more pertinent to suicide ideation. Multiple regression analyses found that hopelessness and depression predicted suicide ideation, whilst anger, disgust and hopelessness uniquely predicted suicidal potential. The clinical and research implications and limitations are discussed within the paper. Paper 3 provides a personal and critical reflection on the research process. It highlights and discusses clinical and theoretical strengths and limitations of the two papers and considers the methodological processes in more detail. Further reflections on how practice could be adapted in line with the findings are given. Future directions for research are considered, in the hope of maintaining the drive for research with this vulnerable and often overlooked population.