The overall aim of this paper is to continue articulating, conceptualizing and discussing the Nordic tradition of educational action research, it´s roots, value base and relevance in the contemporary and globalized world of education (Rönnerman, Furu & Salo, 2008). Firstly, it recognizes and explicates the pedagogical and political influences of the Nordic tradition by anchoring it in (a) bildung as an ideal and process for human growth, (b) folk enlightenment as an arena for realizing bildung and (c) pedagogy as an institutionalized and professional form of fostering and preparing citizens. Study circle and research circle as a site and method for realizing the aims of bildung and folk enlightenment is presented and discussed as a precursor of the Nordic tradition of action research. Secondly, study- and research circles and the Nordic variant of action research as a social practices are further made sense of and analyzed by using the theory of practice architectures to study the sayings, doings and relatings characteristic to it (Kemmis & Grootenboer 2008). This is done in order to establish a dialogue with Anglo-Saxon traditions of action research. Thirdly, the paper presents two recent case studies in which the practices of study and research circles have been used for enhancing teachers´ professional development via peer group mentoring or preparing teacher leaders´ in preschools. These studies function as examples of the relevance of both the Nordic tradition of study/research circles and action research. In both studies the theory of practice architectures are used as means of investigating both the principles and practices of professional development in education. The results of the two studies underline the importance of professionals being able to come together, reflect on their professional practices and being thereby able to participate in the social production of knowledge within their professions.