Aims and objectives: To examine, through the lens of Social Cognitive Theory, the process of change when developing a preparation programme for patients awaiting Total Knee Replacement Surgery. Background: Social Cognitive Theory has been used extensively in occupational psychology to explain and change human actions. It has not been widely used to examine the actions of clinical teams when developing practice. Design: Action research. Methods: Four action cycles were undertaken to develop an information booklet and multidisciplinary Knee Clinic at an acute hospital for patients waiting for Total Knee Replacement Surgery. The process of change, led by a staff and service user Project Management Group, was examined through fieldnotes, interviews, observation and a reflective diary. The data were analysed using the theoretical framework of Bandura’s Social Cognitive Theory. Results: The change process was influenced by personal, environmental and behavioural factors. Self-efficacy and outcomes expectations of staff and service users varied and impacted the level of their involvement in the study. Environmental factors influenced the scope of the project. The behaviour of the Project Management Group facilitated change through the development of team working and involvement in the action cycles. The results of this initiative achieved clinical changes which had not occurred during previous attempts at service development. Conclusion: Social Cognitive Theory is an appropriate and useful theoretical framework both for retrospective analysis and to inform planning of practice changes within the clinical setting.