Social scientists have long been interested in the diffusion of innovations—the process by which new ideas, behavior, and practices spread between persons, organizations, and even countries. While innovations can enter a community through various channels, ongoing spread of innovations through a community occurs through the medium of social networks—collections of interpersonal or digital relationships connecting actors to each other. Social networks are important for diffusion because relationships foster communication, trust, and flow of information. Diffusion outcomes are also shaped by the structural properties of social networks such as density, centrality, and strength of ties, as well as properties of the innovation and the actors involved in the process. The purpose of the article is twofold: (1) to take stock of the field and review ongoing debates on the role of social networks in the diffusion of innovations and (2) to summarize the sociological implications of the diffusion of innovations through social networks.