Most discussions of nationhood are discussions of nations. Nations are understood as real entities, as communities, as substantial, enduring collectivities. That they exist is taken for granted, although how they exist – and how they came to exist – is much disputed.

A similar realism of the group long prevailed in many areas of sociology and kindred disciplines. Yet in the last decade or so, at least four developments in social theory have combined to undermine the treatment of groups as real, substantial entities. The first is the growing interest in network forms, the flourishing of network theory, and the increasing use of network as an overall orienting image or metaphor in social theory. Second, there is the challenge posed by theories of rational action, with their relentless methodological individualism, to realist understandings of groupness. The third development is a shift from broadly structuralist to a variety of more “constructivist” theoretical stances; while the former envisioned groups as enduring components of social structure, the latter see groupness as constructed, contingent, and fluctuating. Finally, an emergent postmodernist theoretical sensibility emphasizes the fragmentary, the ephemeral, and the erosion of fixed forms and clear boundaries. These developments are disparate, even contradictory. But they have converged in problematizing groupness, and in undermining axioms of stable group being.