The establishment of the diffusion theory as an independent research approach in communication science is based on the 1962 publication by Everett M. Rogers, Diffusion of Innovations. Originally stemming from agricultural sociology, Rogers developed a model for the diffusion of innovations in social systems by abstracting numerous empirical findings. The middle-range theory allows this process to be modeled at both the micro and macro level: it identifies determining factors for an individual’s adoption of an innovation as well as at system level. In addition, perceived characteristics of innovations are focused, which can accelerate or slow down the adoption of the innovation for individuals. In communication science, the approach is used in two ways: Firstly, the diffusion of innovations is a communication process driven primarily by mass media and personal networks. Secondly, the adoption of media innovations is often examined. The article provides insight into the life and work of Everett M. Rogers as well as the central contents of the fifth revised edition of Diffusion of Innovations from 2003. In addition, central points of criticism and further developments of the work are addressed.