The no-votes in the French and Dutch referendums heralded the end of the European Constitutional Treaty (ECT). But why did the French and the Dutch voters reject the Constitution? Some commentators have interpreted the No as a protest vote against the national government, others as a reaction to the prospects of Turkish enlargement and more generally as a sign of increasing Euroscepticism among citizens. This article seeks to disentangle the reasons why a majority of French and Dutch voters rejected the ECT. We use both content analysis of media coverage during the campaigns and survey data to analyze the campaign environment and voting behaviour in the two referendums. Our findings suggest that the rejection of the ECT was driven primarily by concerns over specific aspects of the integration project, such as social and economic concerns, rather than general dissatisfaction with the European Union or national governments.