What distinguishes environmental refugees from other refugeesor other migrants? Are all environmental refugees alike? This essay develops a classification to begin to answer these questions and facilitate future policies and research on environmental refugees. Environmental refugees may have considerable control over the decision to migrate, but this varies by the type of environmental disruption. The origin, intention, and duration of environmental disruptions shape the type of refugee. Refugees from disasters and expropriations have limited control over whether environmental changes will produce migration. Gradual degradation allows environmental emigrants to determine how they will respond to environmental change.