This paper attempted to describe the relationships among agricultural extension, rural adult education and community development, which has developed as a disciplinary major (ag. extension in 1971, rural adult education in 1990 and community development in 1997) at the College of Agriculture and Life Science, Seoul National University. Reviewing the related literatures and observing the practical rural development in the Republic of Korea, conclusion was made in such a way that agricultural extension - rural adult education - community development be natural series of disciplinary development process as well as practical development in industrializing and urbanizing country like the Republic of Korea.