The article argues that collective learning plays an important role in the practice of teacher research, which has not yet been adequately dealt with in its theory. Lave & Wenger's (1991) theory of "Situated Learning" is examined as an example for a conceptualisation of collective learning. In the concluding section, some provisions for "learning in communities" in the practice of teacher research are discussed. Although the argument is made for the teaching profession, it is assumed that it also has some bearing on action research in other professions. (Contains 1 figure.)