To call the last ten years a decade of humanitarian intervention requires little imagination. In light of the collapse of the Soviet Union, the end of the Cold War, and the status of the United States as the sole superpower, it seemed that international relations had at last entered a new era in which military operations could be dedicated to humanitarian purposes. To some extent, the ensuing years have seen this promise fulfilled. All of the U.S. military interventions after the Gulf WarSomalia, Haiti, Bosnia, and Kosovohave been described as humanitarian ones. Similarly, many of the U.N. peacekeeping operations in the same period have been described as humanitarian interventions (Somalia and Bosnia again, along with East Timor and Sierra Leone). Now, after a decade of experience, it is high time to assess this kind of military operation with an eye to discerning the role it should play in the global relations of the decade to come.