This article presents the results of a comparative study of genocide prevention showing similarities that form a disappointing pattern of failure on the part of third parties to prevent genocide in three different situations: Rwanda, Srebrenica, and Darfur. Early, clear, and reliable warnings combined with a policy recommendation have not led to preventative action because they were not discussed by the responsible decision makers (Rwanda, Srebrenica) and/or because conflicting international concerns hindered firm action (Darfur). Instruments of prevention were available, in the form of UN peacekeeping troops who could have been empowered for successful prevention in combination with existing reinforcements (e.g., evacuation troops or NATO air support); however, this option was not on the decision makers' agenda. The main explanation for the decisions made by these third parties is their inability to perceive a change from a peace-settlement situation to an emerging genocide and their consequent inability to react to such a change adequately. Rwanda and Srebrenica may be explained in this way, but not Darfur. Here the situation is different and more complicated, as this study shows by reference to the continuing international attention to the situation, on the one hand, and the continuing inability of third parties to change the situation on the ground, on the other. Sudan's political position in the world, as well as the negotiating power the Sudanese government draws from domestic circumstances, has deterred decision makers from initiating measures against Sudan's national sovereignty.