A large gap exists between the results of research concerning efficacious cancer screening programs and the programs delivered in practice. In this article, the authors discuss issues in, barriers to, and lessons learned regarding the dissemination of interventions. They summarize previous reviews, exemplary studies, and theories regarding the diffusion and dissemination of cancer screening interventions. Six lessons learned address the involvement of key stakeholders, factors influencing diffusion, the need for different types of efficacy and effectiveness studies with greater attention to external validity, replication, the use of theoretical and evaluation models, and the importance of policy infrastructure. In this article, the authors make recommendations for future research and practice, including improving the understanding of the intervention process and changing the types of grants funded and review criteria used. Also needed are an enhanced infrastructure, including policies to support dissemination, and the involvement of researchers, health care administrators, clinicians, and funding organizations in dissemination if the gap between research and practice in cancer screening is to be reduced. Cancer 2004. Published 2004 by the American Cancer Society.