Traditional security distinctions are being rapidly eroded. Lines drawn between war and crime are blurring with fateful consequences for divisions between militaries and police forces. The assumption that security should be a publicly provided good has been challenged by private security providers, both domestic and international. Security is no longer (if it ever was) divided between what goes on inside one state and what occurs between states. However, our disciplinary tools for examining these security challenges remain resolutely focused on either the domestic or the international. This book makes one of the first attempts to examine security from both perspectives, bringing together, and into much needed conversation, the fields of criminology and international relations. This book was originally published as a special issue of Global Crime.