This paper presents a method called Topic Change Process Analysis (TCPA). The authors developed this method as a means of analysing therapy transcripts which focus on topic changes related to the verbal client/therapist interaction. Analysis of four eclectic short-term therapies encompass the findings. Therapeutic interventions from different theoretical positions have been identified that include descriptions of interactions influencing topic changes. Finally, TCPA is discussed as a case study method used in therapeutic process research. Such discussion underlines that case study methods should be simple to use. Furthermore, collecting information from several cases to pick up the many variations in client behaviour, therapeutic style, interaction patterns, and adaptation of interventions to the individual client bears importance.