This portfolio thesis comprises of four parts: a systematic literature review paper, an empirical paper, a reflective statement and appendices.Part one is a systematic literature review which examines whether personal therapy is an effective method of professional development for therapists. Quantitative and qualitative literature is critically reviewed. A model of the reported benefits of personal therapy for therapists is proposed. Implications for clinical practice are discussed.Part two is an empirical paper examining the relationship between stage of development and behaviour in clinical supervision for trainee clinical psychologists. Forty trainee clinical psychologists, from three years of a training course, completed a questionnaire (the SLQ-R[A]) measuring their stage of development as supervisees. A subsample submitted DVD-recordings of their supervision sessions which were coded using the Teacher's PET to analyse the supervision behaviours. Comparisons were made between the supervision behaviour of first (n = 8) and third (n = 3) year trainee clinical psychologists and their supervisors. Correlations between questionnaire responses and supervision behaviours were examined. Results are discussed in the context of the Integrated Developmental Model of Supervision. Implications for clinical practice are highlighted.Part three is a reflective statement which considers the process of conducting the research and developing this portfolio thesis.Part four is the appendices.