Form follows function: designs for prevention effectiveness and diffusion research.

Prevention research is at a stage where evidence-based programs and strategies have been identified, and the next question is how to diffuse them. However, the context in which evidence-based programs were first tested and found to be effective may have changed, raising the question of whether the current burden of proof of effectiveness of these programs should be examined before, or at least in conjunction with, diffusion research. This paper discusses, first, contextual changes in testing the effectiveness of prevention programs that have been hitherto identified as evidence-based, and then suggests designs for the next generation of effectiveness trials. Following this, gaps in current diffusion research are discussed according to the four stages of diffusion: adoption, implementation, dissemination, and sustainability, with the major focus on implementation. Designs that may address these gaps in future research are considered, with particular application to prevention research in schools.