The chapter examines warnings relating to violent conflict and massive humanitarian crisis in Darfur, a region of Sudan. As a case of successful ‘crisis warning’ the 2004 Darfur crisis offers important lessons about persuasiveness, especially with regard to the role of senior officials as the chapter focuses on Andrew Natsios, then the administrator of the US Agency for International Development, and Mukesh Kapila, the UN Resident and Humanitarian Coordinator in Sudan. Drawing on extensive original research the chapter shows why these two officials had a variable persuasive impact over time and with different target organisations. The findings suggest that warner capacity and credibility are necessary if not always sufficient for achieving notice and acceptance. Receptivity factors played a facilitating role as they created an environment which was conducive for the warnings being accepted and which reinforced well-tailored warning messages. At the same time, the case shows that warning impact may depend on repeated attempts to get the message across, creativity in exploring alternative channels and routes, and a readiness among sources to take some career risks in order to achieve their intended goal eventually.