In the nineteenth century, European states conquered vast stretches of territory across the periphery of the international system. This book challenges the conventional wisdom that these conquests were the product of European military dominance or technological superiority. In contrast, it claims that favorable social conditions helped fuel peripheral conquest. European states enjoyed greatest success when they were able to recruit local collaborators and exploit divisions among elites in targeted societies. Different configurations of social ties connecting potential conquerors with elites in the periphery played a critical role in shaping patterns of peripheral conquest as well as the strategies conquerors employed. To demonstrate this argument, the book compares episodes of British colonial expansion in India, South Africa, and Nigeria during the nineteenth century. It also examines the contemporary applicability of the theory through an examination of the United States occupation of Iraq.