Thomas W. Valente, PhD, is a Professor in the Department of Population and Public Health Sciences, Division of Health Behavior Research, Institute for Prevention Research, Keck School of Medicine, University of Southern California. He is author of Social Networks and Health: Models, Methods, and Applications (2010, Oxford University Press); Evaluating Health Promotion Programs (2002, Oxford University Press); Network Models of the Diffusion of Innovations (1995, Hampton Press); and over 250 articles and chapters (as of January 2024) on social networks, behavior change, and program evaluation. Valente uses social network analysis, health communication, and mathematical models to implement and evaluate health promotion programs designed to prevent tobacco and substance abuse, unintended fertility, and STD/HIV infections. He is also engaged in mapping community coalitions and collaborations to improve health care delivery and reduce healthcare disparities. He is currently working on specifications for network models of diffusion and contagion with the R package NetdiffuseR; and is also well-known for his work developing network models of program implementation and network interventions.