This chapter is divided into two parts and begins with a review of traditional conceptions of disasters as Acts of God, which are viewed as unforeseeable and therefore beyond human control. It examines the various approaches to the complex task of conceptualising disasters and challenges the notion of disasters being restricted to a particular time or place. Alternative conceptions of disasters with phases of development, both long-term and short-term, are explored. Building on the idea of phases of a disaster, in which systems failures gradually unfold, such long-term histories are theorised in terms of broader contexts of vulnerability in the 1980s in the United Kingdom.