"In the 1970s, Henry Kissinger lamented, 'When I want to call Europe, I cannot find a phone number.' Kissinger's implication was clear: Although Europe was moving towards a union, in reality it was lacking the necessary coherence. Since then, the institutional momentum of the EU towards a common foreign and security policy has increased considerably. Yet, the viability of this institutionalization effort is questionable. This book advances a new perspective on this paradox. It argues that in order to understand institutional success and failure one must investigate the changing cognitive propensities of leaders in key states forming the institution."--Book cover.