Insufficient attention has been given to the ethical and legal questions surrounding mandatory evacuation in disasters and emergencies. We argue that mandatory evacuation orders entail a governmental duty both to provide for people and to decide for people: Government must trigger the provision of critical resources as well as vigorous and persistent efforts to persuade reluctant citizens to leave. Public health professionals, with their experience in weighing costs and risks in the face of uncertainty and balancing individual liberties with the need to protect the common welfare, offer a unique perspective that should be brought to bear in emergencies and disasters.