Theorising NATO builds upon a range of theoretic perspectives to analyze the work of NATO, and its relationship to the European Union. In doing so, it addresses a gap in IR scholarship, allowing the reader to interpret the work of NATO. The book takes into account pluralist theoretic approaches, including tradition modes of realism, liberalism and constructivism, as well as newer approaches such as securitisation and risk. It focuses on how NATO's post-Cold War development might be understood and explained, thus considering the conceptualisation, purpose and future of the Alliance. Theorising NATO will be of interest to students and scholars of International Organisation, International Relations and European Politics.