This monograph weaves together a history of theories of the diffusion of innovations in selected academic disciplines, tracing the influence of these theories in the formulation of national science and technology policies for 1960 to present. The monograph moves along two main warps --disciplinary traditions of diffusion research and a synoptic history of U.S. science and technology policy -- weaving them together at times and in places to demonstrate both their singular threads and crisscrossing patterns. Given the monograph's shifting focus back and forth between intellectual history and science and technology policy history over a 50+ year time period, it is useful to first set out the organization. Section 2 describes the concurrent rapid conceptual development and empirical testing in the 1960-1970s of models of diffusion of innovation in economics, geography, political science, and organizational theory that arose alongside but often in competition with prior "traditions of research" in (rural) sociology and anthropology, and the intra- and interdisciplinary battles over competing theories of diffusion for theoretical/disciplinary hegemony and policy relevance. Section 3 shifts from intellectual history to science and technology history. Section 4 describes the shifts beginning in the 1980s and continuing since then in policy agendas, conceptual models, and framing of U.S. science and technology policies and among OECD nations towards economic growth and competitiveness. Chapter 5 examines the re-emergence in assorted forms of academic interest and external funding in diffusion research circa 2000 to the present, also noting the current limited ties between this research and science and technology policy formulation.