This article describes the design and findings of a case study involving seven groups of teachers at six schools for secondary education. The teachers tried to gain insight into their own practice and to improve their own practice by learning to do action research. They were facilitated by teacher educators over a period of 2 years. The research questions of this paper are: (1) What patterns emerge in the way the teachers master action research? and (2) What patterns emerge in the way they are facilitated by the teacher educators? The theoretical framework of the study elaborates on the performance and facilitation of action research using the concept of praxis . The basic assumption is that teachers learn to do action research by communicating with others about the knowledge they have acquired through experience of action research and the tasks they have performed to develop that knowledge. The results show that what is difficult about learning to do action research is not so much the complexity of procedural and methodological aspects of action research itself, but the fact that teachers have to gradually master several skills and actions at the same time; skills and actions that they are not familiar with. Besides, the study found five developments in professional attitudes that teachers go through as they master action research. Facilitators are increasingly successful the more they offer on-going support on the spot to teachers as they carry out their action research. The study identified five aspects of successful facilitation.