Major findings, interpretations, and policy recommendations developed from a national, in-depth evaluation of the National Diffusion Network (NDN) are presented. Features of the NDN approach to the dissemination of educational innovation include: local change as a goal, use of specialized change agents, emphasis on interpersonal tactics to effect change, and the change agent's orientation for the user of the innovation. Primary goals of this evaluation were (1) to provide a comprehensive description of the evolution, organization, objectives and operating procedures of the NDN, (2) to describe the NDN processes and explain their influence on the adoption of ideas, (3) to evaluate the organizational effectiveness of the NDN and its supporting components, and (4) to analyze evaluation findings and make specific recommendations regarding the continuation of the NDN. These recommendations included awarding specialized technical assistance contracts for operating the NDN, and funding and administering the NDN on as high a level as possible within the Education Division. Among the issues cited for further study were: the role of instructional materials versus in-person assistance in effecting and sustaining change, the patterns and effects of secondary diffusion, the impact of NDN adoptions in terms of conventional educational outcomes, NDN interface with state education agencies, and the problems in effecting changes in urban schools. (MV)