While critical security studies largely concentrates on objects of security, this book focuses on the subject position from which ‘securitization’ and other security practices take place. First, it argues that the modern subject itself emerges and is sustained as a function of security and insecurity. It suggests, consequently, that no analytic frame can produce or reproduce the subject in some original or primordial form that does not already reproduce a fundamental or structural insecurity. It critically returns, through a variety of studies, to traditionally held conceptions of security and insecurity as simple predicates or properties that can be associated or not to some more essential, more primeval, more true or real subject. It thus opens and explores the question of the security of the subject itself, locating, through a reconstruction of the foundations of the concept of security, in the modern conception of the subject, an irreducible insecurity. Second, it argues that practices of security can only be carried out as a certain kind of negotiation about values. The analyses in this book find security expressed again and again as a function of value cast in terms of an explicit or implicit philosophy of life, of culture, of individual and collective anxieties and aspirations, of expectations about what may be sacrificed and what is worth preserving. By way of a critical examination of the value function of security, this book discovers the foundation of values as dependent on a certain management of their own vulnerability, continuously under threat, and thus fundamentally and necessarily insecure. This book will be an indispensible resource for students of Critical Security Studies, Political Theory, Philosophy, Ethics and International Relations in general.