The purposes of this report are: to describe the main elements of the U.S. agricultural extension model and its effects on the agricultural revolution; to analyze attempts to extend this model to non-agricultural technology and/or to less developed countries; and to draw general conclusions about the diffusion of technological innovations, with implications for research and action. The following main elements in the agricultural extension model are identified: a critical mass of new technology; a research sub-system oriented to utilization; a high degree of user control over the research utilization process; structural linkages among the research utilization systems's components; a high degree of client contact by the linking sub-sytem; a "spannable" social distance across each interface between components in the system; evolution as a complete system; and a high degree of control by the system over its environment. The analysis of model application to seven different cases (Social and Rehabilitation Service, Office of Education, National Diffusion Network Program, family planning, developing nations, and diffusion of technology among private manufacturing firms) indicates: little success with SRS application due to the neglect of certain elements of the model; more OE and SRS success; little success when transferred to agricultural applications in developing nations; greatest success with adaptation to the family planning context; and little success in industry applications of the model. (JC)