This book explores the Western secular beliefs that underpin contemporary practices of intervention—most importantly, beliefs about life, death and the dominance of humanity. These beliefs shape a wide range of practices: the idea that human beings should intervene when human lives are at stake; analyses of violence and harm; practices of intervention and peace-building; and logics of killing and letting die. Ironically, however, the Western secular desire to ensure the meaningfulness of human life at all costs contributes to processes of dehumanization, undercutting the basic goals of intervention. To explore this paradox, International Intervention in a Secular Age engages with examples from around the world, and draws on interdisciplinary sources: anthropologies of secularity and IR, posthumanist political philosophy, ontology and the sociology of death. This book offers new insight into perennial problems, such as the reluctance of intervenors to incur fatalities, and international inaction in the face of escalating violence. It also exposes new dilemmas, such as the dehumanizing effects of quantifying casualties, Western secular logics of killing, and the appropriation of lives and deaths through peace-building processes. It will be of great interest to students and scholars of international relations, political philosophy, international ethics and social anthropology.