Social movements are ubiquitous in political life. But what are they? What makes someone a member of a social movement, or some action an instance of movement activity? Are social movements compatible with democracy? Are they required for it? And how should individuals respond to movement calls to action? Philosophers have had much to say on issues impinging on social movements but much less to say on social movements as such. The current article provides a philosophical overview of social movements. (...) To do so it canvasses contemporary work on the nature of shared agency and collective action, social epistemology, democratic theory, and the theory of individual responsibility for structural injustice. The article finds that contemporary analytic philosophy has considerable work to do if it is to account for the nature, epistemology, ethics, and politics of social movements. There may be more things in the streets than are dreamt of in our philosophy. (shrink)