The aim of this chapter is to provide background information about the political context in which the debate on the Charlie Hebdo attacks developed within the different national arenas. Besides some general political trends developing at the European level (including the financial crisis and its political consequences), Chapter 2 presents the main dimensions of political opportunities and constraints that are susceptible to explain cross-national differences in collective actors’ claiming, framing, and justifying. In particular, it zooms in on two sets of dimensions that social movement studies have considered relevant: factors that can influence public debates over migration and ethnic relations in general—i.e., national citizenship regimes—and factors which pertain more specifically to debates about Muslims and Islam in the secular public sphere—i.e., the regime addressing Church–State relations. The chapter then presents a quantitative empirical analysis of political claims-making in France, Italy, Germany, and the United Kingdom, during the first month following the 2015 attacks. Despite substantial cross-national differences in terms of discursive and political opportunities, the analysis of the content of the debate in the European public sphere shows that most of the mass media attention was devoted to the issues of security and freedom of expression (highly visible and non-divisive issues), which triggered much less political conflict than stories about Islam, discrimination, and migration.