This thesis is a single case study of my work as therapist with four different participants from a community-based treatment programme for adolescents who have sexually offended. Using an autoethnographic approach, the study seeks to contribute to understanding of how the therapeutic use of self can work to enhance the effectiveness of the treatment process. Central to this argument is the principle of optimal responsiveness, developed by Howard Bacal (1985). Optimal responsiveness is founded in specificity theory, which argues that we cannot predict in advance what intervention is going to be effective, because of the uniqueness of each therapeutic encounter: hence the importance of the individual practitioner‟s clinical judgment. I locate the theoretical understanding of the therapeutic use of self in the tradition of judgment-based practice (Polkinghorne, 2004). The research explores two questions: How might the therapist use their experience of self (their subjective and intersubjective experience) to guide their sense of being optimally responsive? How might research into the therapist‟s experience of their use of self in therapy contribute to the integration of the personal and professional self of the therapist? The findings are expressed in the form of four autobiographic stories and four therapy stories. The autobiographic stories show how the personal life experience of the therapist is integrated with the process of clinical judgment. The findings are analysed from the perspectives of systemic-narrative therapy and relational psychoanalytic therapy. I identify a number of examples of how the use of self mediated a variety of intentional therapeutic interactions such as reflexive questions, interpretations and self-disclosures and spontaneous interactions such as playful improvisations and the experience of intimacy. I argue that self reflexivity is at the heart of these processes. The thesis shows the relevance of autoethnographic case study research to the practice of therapy in general and it shows how case study research can complement experimental research. This research also has a number of important implications for professionals working as therapists in the sexual offending fields. I argue that the risk-need-responsivity rehabilitation model will be strengthened by giving closer attention to the neglected principle of professional discretion; and that the effective implementation of evidence-based procedures is dependent upon the practical wisdom of practitioners. The research alerts therapists to the importance of paying attention to integrating their professional and personal selves as part of their ongoing professional development. The research highlights the relevance of the subjective experience of cultural discourse, in particular the social construction of masculinities, an area that often goes under-represented in the delivery of adolescent sexual offending programmes. The findings also support the argument that the experience of caring for and being cared for is central to treatment, and that self reflexivity can be both a process and an outcome goal for all therapy participants, both client and therapist. Finally, my research also demonstrates how the practice of honest introspection by the therapist can mitigate against the temptation (which is always there) to get caught up in viewing the person who committed an offence as the “other”.