Over recent years, social movements formed in response to austerity measures have played an increasingly important role in referendums. This is the first book to bridge the gap between social movement studies and research on direct democracy and draws on social movement theory to understand the nature of popular mobilization in referendums. The book uses unique case studies such as the Scottish referendum, the independence consultations in Catalonia, the Italian water referendum, the Troika proposals in Greece and the Iceland debt repayment referendum, to illustrate the ways the social movements have affected the referendums' dynamic and results. It also addresses the way in which participation from below has had a transformative impact on the organisational strategies and framing practices used in the campaigns.