The context of the emergence of action research is explored historically and comparatively. The primary focus is a description of the development of action research in the middle part of this century in the United States. Certain assumptions, intentions, and practices of educational action research as they emerged in the early stages of development are explained. Some central aspects of educational action research, both in the present and in earlier areas, are identified. Areas of focus include the following: democracy, social engineering, and social change; research for re-education; curriculum studies and the science of education; growing up in educational practice; the method of science; depoliticizing action research; inservice and personal development; persistent themes in action research; and understanding action research today. Though action research declined in prominence in the late 1950s, it remained consistent. In the 1970s action research continued in several areas. The strongest theme is the idea of the teacher as researcher. Other themes in many of the recent action research projects are the knowledge-practice gap, issues of race, class, and gender, demographic changes in the school population, and school-based alternative models for curriculum development. Contains about 97 references. (SM)