This article examines the concept of boundaries, by putting an emphasis on the utility of the concept for the study of relational processes. Literatures on collective and social identity; ethnic/racial, class, gender/sex inequality; knowledge, professions and science; as well as national identities, communities and spatial boundaries are discussed. The similarity of processes that are at work across different social worlds and locations as well as in a range of institutions are highlighted. Finally possible development paths for the future elaboration of the concept are proposed.
