As we write this, scenes of struggle on the streets of Europe, of official policy increasingly at odds with popular opinion, and a massive crisis of legitimacy spreading across many countries are repeating a drama familiar since the events of 1789-92, 1830 and 1848 - described in 1850-5 by Lorenz von Stein as “the social movement”. In the uneven and contradictory struggle for substantive democracy across the last quarter-millennium in Europe, unofficial popular agency keeps reappearing as a central figure on the European stage, with a wide variety of forms, issues and ideologies. Research on social movements in this broad sense is a long-standing feature of European Studies under many disciplinary headings: sociology, political science, history, anthropology, geography, industrial relations, women’s studies and so on, and is routinely invoked as part of the background of the study of literature, popular culture, philosophy etc. When social movements have been part of the making and unmaking of states or threatened to become so - as in 1789-1815, 1848, 1871 in France, 1916 – 1923, 1943-45, 1967 – 69, 1975 in Portugal, 1980-1 in Poland, 1989-90 and arguably again since the turn of the millennium – they can be so omnipresent as to be taken for granted. At other times, such as between 1968 and 1989, the established order and its routines can seem so firmly in control of the institutional (and military) reins that movements are analysed only at their own assigned “level” of action. In a longer perspective, one of the most important features of social movements as collective popular agency is precisely their waxing and waning: if at one time a “movement” consists of a handful of NGOs or intellectuals, at another it is a piece on the strategic chessboard, and at yet another it may be rewriting the rules of the political game.