On August 8, the World Health Organization (WHO) Director-General Margaret Chan declared the West Africa Ebola crisis a “public health emergency of international concern,”1 triggering powers under the 2005 International Health Regulations (IHR). The IHR requires countries to develop national preparedness capacities, including the duty to report internationally significant events, conduct surveillance, and exercise public health powers, while balancing human rights and international trade. Until last year, the director-general had declared only one such emergency—influenza AH1N1 (in 2009). Earlier this year, she declared poliomyelitis a public health emergency of international concern and now again for Ebola, signaling perhaps a new era of potential WHO leadership in global health security.