How do we know when we are investing wisely in security? Answering this question requires investigating what things are worth securing (and why), what threatens them, how best to protect them, and how to think about it. Is it possible to protect them? How best go about protecting them? What trade-offs are involved in allocating resources to security problems? This book responds to these questions by stripping down our preconceptions and rebuilding an understanding of security from the ground up on the basis of a common-sense ontology and an explicit theory of value. It argues for a clear distinction between objective and subjective security threats, a non-anthropocentric understanding of security, and a particular hierarchy of security referents, looking closely at four in particular-the ecosphere, the state, culture, and individual human beings. The analysis will be of interest not only to students and scholars of International Relations, but also to practitioners. David A. Welch is University Research Chair and Professor of Political Science at the Balsillie School of International Affairs, University of Waterloo. His previous books include Justice and the Genesis of War (Cambridge University Press, 1993), which won the 1994 Edgar S. Furniss Award for an Outstanding Contribution to National Security Studies, and Painful Choices: A Theory of Foreign Policy Change (2005), which was the inaugural winner of the International Studies Association International Security Studies Section Best Book Award. He is currently co-editor of the Cambridge University Press journal, International Theory"--