Our concern in this chapter is with constructions of the Unions collective identity and its associated roles in international affairs. These, we believe, impact significantly upon practices towards third parties. The relationship between identities, interests and behaviour, however, is neither simple nor linear. Identities do not directly determine interests, rather they perform a mediating function. Thus understandings about the external context of ideas and events, or the appropriateness or feasibility of alternative courses of action, are shaped by identity constructions that are themselves shifting and contested.