European and American specialists in economic and political processes move beyond earlier debates to look seriously, systematically, and innovatively at social change and protest, with particular attention to the influence of economic change and variation on contentious politics. The essays take up two widely recognized but much contested questions in contentious politics: how threats and opportunities faced by potential participants in joint political action affect the likelihood, character, and consequences of that action; and, how economic change and variation either a) constitute significant political threats and opportunities or b) shape responses to political threats and opportunities. Contributors: Maria Kousis, Charles Tilly, Marc Giugni, Julie Berclaz, Marc Steinberg, Jeffery Broadbent, Klaus Eder, John K. Glenn, Dieter Rucht, Richard Hogan, Maryjane Osa, Cristina Corduneanu-Husi.