This entry describes the core propositions, theoretical frameworks, key concepts, and empirical research of media dependency theory. Media dependency theory provides a multilevel and ecological framework to explain individual‐level and societal‐level conditions that influence the degree of importance of media in individuals' everyday lives. Following a theoretical discussion, empirical studies that apply media dependency theory are discussed. The entry explains how media dependency theory, which was first proposed in the 1970s, when the mass media was more dominant, has evolved since then.