Forty Years of Diffusion of Innovations: Utility and Value in Public Health MUHIUDDIN HAIDER Department of Global Health, The George Washington University School of Public Health and Health Services, Washington, DC, USA GARY L. KREPS Health Communication and Informatics Research Branch, National Cancer Institute, Bethesda, Maryland, USA This special issue is created to mark the 40th anniversary of Everett Rogers’ Diffusion of Innovations (DOI) model. Diffusion is the process through which an innovation, defined as an idea perceived as new, spreads via certain communication channels over time among the members of a particular social system. A great deal of research in a variety of academic disciplines (about 5000 published studies so far) has been con- ducted on the diffusion of innovations over the past six decades. The areas of application for these studies range from hybrid seed corn to modern math, to the snowmobile to antibiotic drugs, to HIV/AIDS prevention (Rogers, 1995). These investigations have led to a general model of the diffusion of innovations, which can be applied to the recent spread of the Internet or to any other new idea. Everett Roger’s ground-breaking model has contributed to a greater understanding of behavioral change, including the variation in rates of adoption of innovations, and it has held a broad scope of practical applications in the field of public health. The 40th Anniversary of DOI symposium, held at The George Washington University in April 2002, brought together a diverse group of national and international scholars representing academic and research and development agencies who presented papers and engaged in thought-provoking dialogue discussing the various applications of DOI for promoting public health. A number of the papers presented at the symposium are included in this issue. They are categorized into three areas: 1. theoretical assessment of DOI, 2. methodological evaluation of DOI studies, and 3. application of DOI in public health best practices. Diusion of Innovations: An Overview Improving the application of the DOI model in the field of public health can lead to advances in health promotion and disease prevention on a global level. As defined previously, diffusion is the process by which an innovation is communicated through certain channels over time among the members of a particular social system. This process includes both the planned and spontaneous spread of new ideas (Rogers, 1995). Journal of Health Communication, Volume 9: 3–11, 2004 Copyright # Taylor & Francis Inc. ISSN: 1081-0730 print/1087-0415 online DOI: 10.1080/10810730490271430 3