Book excerpt: Collective Securitisation and Security Governance in the European Union presents an integrated theory of collective securitisation – a theoretical foundation for explaining how the process of collective securitisation sustains and makes effective an identifiable system of regional security governance. The volume demonstrates the empirical utility of collective securitisation in the EU security space through a set of structured case studies focusing on the collective securitisation of terrorism, cyberspace, migration, energy, health and climate change. The contributions to this collection address three questions: Under what conditions does collective securitisation occur? How does collective securitisation affect the scope and domains of EU security governance? And how does collective securitisation explain the emergence of the EU system of security governance? This volume breaks new ground in the field of EU security studies and provides a theoretical orientation that contributes to our understanding of how and why the EU has developed as a security actor in the 21st century. Developing and testing the theory of collective securitisation with reference to some of the most pressing contemporary security issues, Collective Securitisation and Security Governance in the European Union will be of great interest to scholars of the European Union and Security Studies. The chapters were originally published as a special issue of West European Politics.