Even though evidence-based knowledge is considered the foundation of clinical practice, many clinicians question the clinical relevance of published research. Clinicians increasingly define themselves as having an integrative stance, in contrast to the tendency for most research to be based on clearly defined psychotherapies. Qualitative single case studies make it possible to generate knowledge about what actually occurs in integrative therapy. Topic change process analysis (TCPA) is used in the analysis of brief integrative therapy conducted by a very experienced psychotherapist drawing on a complex variety of therapeutic approaches. The client was a man in his late thirties, worrying about his strong anger, particularly related to one of his children. Analysis of topic areas, topic shifts, response patterns within topics and changes in perspective made it possible to identify key processes and key patterns of the therapy which resulted in a very positive outcome for the client. Implications of these findings for practice, and future research, are discussed.