On the assumption that the North American city and regional planning education has been of questionable value for underdeveloped countries, this study examines two major questions: a) how has this education system responded to the academic needs of planning students from underdeveloped countries? b) what was the outcome of this response. Answers to these questions demonstrate a theory of international interaction. In essence, a similar problem in many nations triggers sequential response in the form of interest, involvement, and influence among international agencies, national governments and educational institutions. The effect of this process is two-directional: changes occur in both interacting systems, i.e. in the relevant problem (here planning education for underdeveloped countries) and in the institutions (here North American planning schools). Both the pedagogic changes and the underlying processes have been studied with the help of data collected from a field survey of North American planning schools and agencies involved in international education. The technical assistance programs of international and national agencies led to the increased involvement of North American planning schools, in planning education programs of underdeveloped countries. Educational exchange programs increased more rapidly in the 1960s compared with the 1950s due mainly to the launching of the United Nations Concerted Action Program in 1961, the adoption of the Alliance of Progress Charter in 1961, the increased coverage of the Canadian Technical Assistance Program since 1958 and the passage of the Foreign Education Act of the United States in 1966. Starting from the late 1950s, many underdeveloped countries established planning schools with the help of international agencies and foreign planning schools. These schools were in addition to the ones established entirely through national means. A comparative study of these two models shows that the internationally-developed schools have programs more attuned to the needs of the recipients. These schools are built on an image of planning which has a regional and a developmental orientation. The international interaction also led to the changes in North American planning education. Whereas no planning school had a course on the themes of underdeveloped economies twenty years ago, today 21 schools offer 39 such courses, the majority of which were opened in the late 1960s. These courses were first introduced in the few, relatively senior schools such as Harvard, M.I.T and Yale. From these centers, the interest spread to other schools through a "dissemination process". Courses on underdeveloped countries have been introduced in schools which have a high enrollment of students from those countries, a high proportion of internationally-experienced faculty members, a high standing as centers of education and research, and a large number of university-wide international programs supported by outside agencies. These schools are among the senior ones situated in a region which has the largest segment of foreign student population, the highest density of academic activities and the largest number of agencies, institutions and professional participating in international programs. Interest has now reached a point at which the field of concentration on underdeveloped countries has attained a validity of its own. The discernible trends suggest some guidelines. The institutional and interdisciplinary setting for planning programs in underdeveloped countries must recognize the shifting emphasis of planning from physical to socio-economic aspects, from local to regional scale and from routine skills to innovative knowledge. The underdeveloped countries can be better served if North American planning schools concentrate their international efforts in selected planning schools, restrict admission to the mature and potentially capable students, improve the theoretical and analytical base of the overgeneralized courses and increase international institutional collaboration. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate