The number of independence referendums over the last years has increased dramatically. Nevertheless, these regional consultations have not always been welcomed by the governments of the countries involved. While institutional collaboration in Scotland led to the organisation of an inclusive electoral process in 2014, the Catalan case ended in a unilateral ballot that was repressed by Spanish police forces in 2017. How to explain such a contradiction? This book aims to provide answers to this question by focusing on the decision-making processes affecting central state governments. Independence referendums are frequently presented as neutral mechanisms for resolving conflicts between two principles: the aspiration of territorial minorities to self-determination on the one hand and the will of sovereign states to protect their territorial integrity on the other. Nevertheless, their politics is much more complex as demonstrated by the following chapter.