 The topic of scientific revolutions has been philosophically important since Thomas Kuhn’s account in The Structure of Scientific Revolutions (1962, 1970). Kuhn’s death in 1996 and the fiftieth anniversary of Structure in 2012 have renewed attention to the issues raised by his work. It is controversial whether or not there have been any revolutions in the strictly Kuhnian sense. It is also controversial what exactly a Kuhnian revolution is, or would be. Although talk of revolution is often exaggerated, most analysts agree that there have been transformative scientific developments of various kinds, whether Kuhnian or not. However, there is considerable disagreement about their import. The existence and nature of scientific revolutions is a topic that raises a host of fundamental questions about the sciences and how to interpret them, a topic that intersects most of the major issues that have concerned philosophers of science and their colleagues in neighboring science and technology studies disciplines. Even if the so-called Scientific Revolution from Copernicus to Newton fits the attractive, Enlightenment picture of the transition from feudalism to modernity (a claim that is also contested), the putative revolutions in mature sciences (e.g., relativity and quantum mechanics) challenge this Enlightenment vision of permanent rational and methodological standards underlying objective sciences and technologies that lead society along the path of progress toward the truth about the world. Today’s scientific realists are the most visible heirs of this picture. Although many philosophers and philosophically or historically reflective scientists had commented on the dramatic developments in twentieth-century physics, it was not until Kuhn that such developments seemed so epistemologically and ontologically damaging as to seriously challenge traditional conceptions of science—and hence our understanding of knowledge acquisition generally. Why it was Kuhn’s work and its timing that made the major difference are themselves interesting questions for investigation, given that others (e.g., Wittgenstein, Fleck, Bachelard, Polanyi, Toulmin, and Hanson) had already broached important “Kuhnian” themes.