This book presents a key to understanding how ideas, products, opinions, and so on take off and spread throughout society, and provides a better means to estimate how fast or slow that spread occurs. This spread is referred to as the diffusion of innovations. The diffusion of innovations occurs among individuals in a social system, and the pattern of communication among these individuals is a social network. This book analyzes how social networks structure the diffusion of innovations.

Chapter 1 reviews diffusion of innovations theory, network analysis, and the datasets used as examples. Chapter 2 provides a review of prior research, and chapter 3 provides relational network models of diffusion which posit that individuals adopt innovations based on their direct relations with others in their social system. Chapter 4 provides structural network models of diffusion which posit that individuals adopt innovations based on their position in the social system. Chapters 5 and 6 present threshold and critical mass models of diffusion. Chapter 7 develops a general threshold model of adoption based on social networks.

This book is addressed to researchers, policymakers, and students interested in the diffusion of innovations or network analysis and to individuals interested in studying the process of social change as represented by a diffusion/network paradigm. Finally, individuals interested in developing, evaluating or understanding communication campaigns and media effects can use these concepts to improve their work.

Thomas W. Valente is a Professor and Director of the Master of Public Health Program in the Department of Preventive Medicine, 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 100 articles and chapters 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. Valente received his BS in Mathematics from the University of Mary Washington, his MS in Mass Communication from San Diego State University, and his PhD from the Annenberg School for Communication at USC. He is currently a visiting Professor the École des Haute Études en Santé Publique.