This study aimed to gain an understanding of the aspects of trauma-focused cognitive behavioural therapy (Trauma-Focused-CBT) for post-traumatic stress disorder (PTSD) that service-users find important in contributing to their improvement. Nine people (5 females and 4 males, mean age 53 years old who had received on average 12 sessions of Trauma-Focused-CBT) who reported a significant reduction in their symptoms following treatment of PTSD took part in semi-structured interviews. Interpretative phenomenological analysis identified five themes: Living with Symptoms before Therapy; Feeling Ready for Therapy; Being Involved; Bringing About Therapeutic Change; and Life After Therapy. This study contributes towards a clearer understanding of the aspects of the Trauma-Focused-CBT process that service-users found important in aiding their improvement. In particular, it highlights the central role that participants attributed to their own involvement in the therapeutic process and how much they valued this. Limitations and future directions are discussed.