Action research began as an ambitious epistemological and social intervention. As the concept has become reified, packaged for methodology textbooks and professional development workshops, it has degenerated into a cure that may be worse than the disease. The point is not the trivial one that action research, like any practice, sometimes shows up in cheap or corrupt forms. The very idea that action research already exists as a live option is mystifying, distracting us from the deep challenge that action research ultimately represents. Though Joseph Schwab is sometimes credited as a forerunner of action research, it is likely that he would see the new talk of "the teacher as researcher" as indicative of the very epitomization of which he warned. Dewey's new conception of knowledge, action, and communication--and the vision of the teacher as learner it entails--requires nothing short of a radical rethinking of teaching and inquiry, schooling and teacher education. This essay recalls the promise of action research, exploring its pitfalls, and attempts to get clear on the ongoing challenge it represents.