The juxtaposition of action and research conveys a sense of the richness and complexity of action research, yet it does not entirely translate its nuanced and sophisticated philosophy. In turn, an understanding of this philosophy is crucial for grasping action research’s radical originality. In this context at least, it may be more accurate to define action research by drawing on the term practice, even though it does not form part of the basic conceptual pair. Not only does practice make it easier for us to trace the constellation of philosophical influences behind the theory and practice of action research—from pragmatism to postmodernism, including Greek philosophy and Marxist and psychoanalytic schools of thought—but also to identify where these influences end and action research emerges as the bearer of a nontransferable view. Beyond this, at the heart of action research lies a structural affinity with singular social practices, which are its key ontological sites—that is, the context where action research in each case fills its epistemological and ethical dimensions with meaning. What kind of knowledge does action research aim to produce? What behaviors do action researchers engage in? Compared to other research paradigms in the social sciences—the field of education included—the specific quality of action research has to do with how its epistemological and ethical dimensions are shaped not from without but from within any given social practice. This is the key to its specific ecology. In action research, the epistemological and ethical realms do not stand beyond or above the situated social practices, with their values, principles of procedure, knowledges, and discourses, including their own literacies and modalities—in short, their own internal cultures. Action research conceives and presents itself as a rational and systematic way for members of the different social practices to build and rebuild their own epistemologies and ethics precisely by drawing on, and selecting from, their own internal cultures. How does this ecological perspective translate itself in education? Education is one of the key areas in which action research is generally applied, together with welfare and healthcare. Yet apart from the specific use of action research by educators, action research carries within itself a specific educational philosophy (and a political philosophy as well) which underlies its application, regardless of the specific social practice in which it takes place. In the same way that action research is politically democratic, educationally speaking action research is participatory, meaning that learning, improvement, or development can only be realized through a self-determining process in which people act and research freely upon and among themselves. This is precisely what action research facilitates in the different social practices. Action research is always educational, whether one develops it in education, welfare, or healthcare. As a result, action research has contributed a clear-cut pedagogical model that some critical educators have already imported to their own educational institutions and practices: youth participatory action research.The juxtaposition of action and research conveys a sense of the richness and complexity of action research, yet it does not entirely translate its nuanced and sophisticated philosophy. In turn, an understanding of this philosophy is crucial for grasping action research’s radical originality. In this context at least, it may be more accurate to define action research by drawing on the term practice, even though it does not form part of the basic conceptual pair. Not only does practice make it easier for us to trace the constellation of philosophical influences behind the theory and practice of action research—from pragmatism to postmodernism, including Greek philosophy and Marxist and psychoanalytic schools of thought—but also to identify where these influences end and action research emerges as the bearer of a nontransferable view. Beyond this, at the heart of action research lies a structural affinity with singular social practices, which are its key ontological sites—that is, the context where action research in each case fills its epistemological and ethical dimensions with meaning. What kind of knowledge does action research aim to produce? What behaviors do action researchers engage in? Compared to other research paradigms in the social sciences—the field of education included—the specific quality of action research has to do with how its epistemological and ethical dimensions are shaped not from without but from within any given social practice. This is the key to its specific ecology. In action research, the epistemological and ethical realms do not stand beyond or above the situated social practices, with their values, principles of procedure, knowledges, and discourses, including their own literacies and modalities—in short, their own internal cultures. Action research conceives and presents itself as a rational and systematic way for members of the different social practices to build and rebuild their own epistemologies and ethics precisely by drawing on, and selecting from, their own internal cultures. How does this ecological perspective translate itself in education? Education is one of the key areas in which action research is generally applied, together with welfare and healthcare. Yet apart from the specific use of action research by educators, action research carries within itself a specific educational philosophy (and a political philosophy as well) which underlies its application, regardless of the specific social practice in which it takes place. In the same way that action research is politically democratic, educationally speaking action research is participatory, meaning that learning, improvement, or development can only be realized through a self-determining process in which people act and research freely upon and among themselves. This is precisely what action research facilitates in the different social practices. Action research is always educational, whether one develops it in education, welfare, or healthcare. As a result, action research has contributed a clear-cut pedagogical model that some critical educators have already imported to their own educational institutions and practices: youth participatory action research.