Genocide is a unique crime against humanity. This crime is currently unfolding in Darfur, western Sudan, as the world looks on. Yet, even as pressure grows from many quarters (including Congress) for U.S. leadership regarding Darfur, many progressives and people usually concerned about social justice feel that a U.S.-led intervention is the wrong answer. They express concern about negative historical precedents, about exploitative U.S. motivations, and about the current lack of U.S. credibility on the international stage. These are all defensible arguments. But do they render U.S. leadership an impossible option in the case of genocide?