The division of the communication discipline according to whether people communicate face-to-face or via a technological medium has shaped the field's development from the outset. The divide has been institutionalized over time in the structures of academic departments and schools, professional training and degrees, scholarly societies and publishing, and in the field's larger research agendas. However, critics inside and outside the field have long insisted that the differences between the two subfields actually obscure the shifting, contingent nature of communication in everyday experience, social formations, and culture. This paper traces efforts to theorize the intersection of interpersonal and media communication, and in particular the concept of mediation, from Lazarsfeld and Katz's two-step flow in the 1950s, to the challenge of digital media technologies in the 1970s and 1980s, to the rise of new media studies and digital culture scholarship from the 1990s onward.