This thesis discusses a new and unexplored concept which uses computer assisted technology to support trauma-focused psychotherapy, focusing on restructuring and relearning of past events. The proposed application allows patients and therapist to visualize the patient’s past experience using maps, personal photos, stories and self created 3D virtual worlds. The tool aims to allow patients to restructure, reappraise and relearn about their past experience involving the problematic stressors. The design of the system followed a situated cognitive engineering approach. The first step of this approach was to do a domain analysis. This was done in close cooperation with a psychiatrist experienced in treating veterans suffering from a combat-related PTSD, which eventually lead to the establishment of an inventory of human factor knowledge, operational demands and envisioned technology. The knowledge was used to create several scenarios and prototypes. Experts with a psychology background were asked to review these scenarios and discuss various possibilities and limitations, while prototypes were evaluated and tested by experts with a background in Human-Computer Interaction. The acquired feedback made it possible to constantly refine the requirements baseline. The experiment which followed suggested that all three main interface components were easy to use. Also, differences were found in a way a story was told with the application compared to a story told without the use of the system. The results hinted at a more structured and precise way of storytelling. A case study with a veteran showed that the patient enjoyed working with the application. He felt encouraged to work with it as he saw the purpose of talking about past events by managing a media archive.