For about two decades only marginal relevance was attributed to action research as a research strategy by large sections of the German social science community. The growing international debate on key concepts such as community participation, community-based participatory research and participatory action research were largely ignored. In this paper we want to clarify our concept of action research and to provide arguments for the need to re-evaluate the research potential of this approach. We illustrate the arguments by an analysis of one of the most successful in-service education of teachers' courses in Austria, which is based on action research ("Education and subject matter didactics for teachers"). The second part of the paper argues that the growing number of practical action research examples in German-speaking countries indicates a social demand for this type of research. The paper ends with a theoretical discussion of frequent objections against action research in the German research tradition. (Contains 4 notes.)