This thesis concerns the use of repertory grids to examine personal and professional development (PPD) during professional training programmes. Paper one consists of a systematic review of 11 repertory grid studies of people undergoing training in human services professions. The findings suggest that professional socialisation occurred in line with the aims of training programmes but was an idiosyncratic, non-linear process which continued post-qualification. Trainees' thinking style became more abstract, less polarised and more cognitively complex. Implications for people training in human services professions and training providers are discussed and suggestions for improved future research are provided. Paper two reports a repertory grid study examining 26 third-year trainee clinical psychologists' construal of their PPD. The findings suggest that trainees' personal and professional selves were construed to be similar to each other. Trainees reported feeling anxious, stressed, unsettled and lacking an appropriate work-life balance. These difficulties were attributed to the demands of training and were expected to resolve once training was completed. Suggestions for future research with improved methodology are made and the implications of the findings for trainees, training providers and employers of newly qualified clinical psychologists are given. Paper three provides a critical reflection of the thesis; discussing the strengths and limitations of each of the papers and concluding with the author's personal reflections on the process of the research and her own PPD.