Progression of therapy research and clinical application of treatment require better understanding of the change process.

The stage model of therapy research focuses on the development of treatment from pilot work, through randomized controlled clinical trials, to tests in clinic settings. A goal of the model is to develop effective treatments that can be used clinically. The present comments begin with a similar goal but emphasize the importance of a broader agenda designed to understand therapy. A central thesis is that developing effective treatments depends heavily on investigations that address critical scientific questions; particularly, what are the mechanisms through which therapy operates and under what conditions is therapy likely to be effective and why? The comments argue for a portfolio of research that addresses a broader range of questions and encompasses more diverse methods of evaluating treatment. Breadth and diversity are not ends in themselves but will be essential to obtain the requisite knowledge to effect optimal changes in clinical applications of treatment.