Diseases that affect people and have their origins in animals (zoonoses) have the potential to cause social, political and economic upheaval, often with little warning. Witness 2014’s Ebola outbreak in West Africa, as well as recent avian (H5N1) and swine (H1N1) flu pandemics. Other zoonoses less dramatically, but with wider impact, quietly devastate lives and livelihoods, an added burden in the lives of poor people in poor countries. Growing attention is being paid to integrated, One Health approaches to zoonoses, which involve animal and human health professionals, as well as wildlife, environmental and other specialists. However, practice on the ground is less informed by this ideal and more by approaches rooted in political understandings of disease. To progress with One Health, it is therefore essential to understand the context in which policymakers are operating.