In the wake of World War II, the United States and its allies developed a new type of security arrangement in which a state could maintain a long-term, peacetime military presence on the territory of another equally sovereign state that, unlike earlier practice, was not tied to occupational regimes or colonial rule. The impact of this development on international politics is hard to overstate, and it has become a constitutive feature of contemporary security dynamics. Despite its significance, the origins of this basing practice have remained largely understudied and unexplained. In Armed Guests, Sebastian Schmidt develops a theory to explain the emergence of this phenomenon, which he calls "sovereign basing," and in doing so, shows how its development fundamentally transformed state sovereignty and the very nature of security politics. He applies concepts derived from pragmatist thought to a historical study of the relations between the United States and its wartime allies to explain how sovereign basing originated through the efforts of policymakers to come to grips with the unique security environment of the postwar era. As he argues, the tools offered by pragmatism provide needed analytical leverage over the emergence of novelty and offer valuable insight into the dynamics of stability and change. Armed Guests is a wide-ranging account of the development of sovereign basing practices in the years before and after World War II. It is a book with significant implications for our understanding of contemporary security politics and the future of basing strategies as well as for broader issues in IR, including the sociological foundations of security strategies, the nature of norms, and the practice of sovereignty.