Clinicians keep looking for new ways to improve patient treatment and if you are involved in health services delivery and quality development you try to improve the performance of your organisation.However, our experiences are often not communicated to others and do not contribute to an accumulation of knowledge on how change is best brought about. In this article we argue that the design and testing of interventions intended to change professional performance from their conceptions should include theoretical considerations of the complexities of implementation and we further suggest a stage approach in the development of such interventions. In the preclinical stage anintervention model is developed based on theoretical understanding and empirical research. In stage I you experiment with elements of the intervention. In stage II the intervention is tried in full scale in selected units of the target group. Stage III is a controlled randomised clinical trial and stage IV evaluates the routine intervention delivery.