This chapter argues that Hannah Arendt's distinctions between labour, work and action, as these are discussed in Human Condition (HC), are best understood as a set of claims about the fundamental structures of human societies. It explores her work in terms of both her historical/institutional account of the development of a public oikos, and in terms of her account of the rise of capitalism and of civil society that appears in her early work. The chapter develops the idea that the realm of action can be understood as a distinct realm of society, with which the properties of freedom, boundlessness, irreversibility and unpredictability are explicitly identified. It demonstrates the explanatory power of this interpretation in, which deals in greater in detail with the concept of power, and in, in which it discusses advanced technoscientific knowledge as a form of action. The chapter also argues that it also stands close to phenomenological social inquiry, of the kind pioneered by Alfred Schutz.