Legal scholars, as well as economists, have focused limited attention on the role of coordinated groups of market participants - committees, clubs, associations, and the like - in social ordering generally and in the evolution of norms particularly. One might trace this neglect to some presumptive orientation to state actors (expressive law) and autonomous individuals (norm entrepreneurs) as the sole parties of interest in social change. Yet, alternative stories of social ordering and norm change might also be told. Dramatic recent changes in the contracting practices of the sovereign debt markets offer one such story.

Using the latter by way of illustration, this essay explores the potential role of groups as mechanisms of norm transformation. In appropriate circumstances, it suggests, groups may offer an intermediate path of change between regulatory mandate and decentralized markets. Where a pattern of private behavior is at once inefficient but resistant to decentralized market change, groups may effectively stand in for the market - relying on private rather than public incentives to define outcomes, yet offering an infrastructure of coordination lacking in a pure market dynamic. Building on this conception, the essay offers a potential framework for the analysis of groups - as market substitutes in their internal dynamics, as market-mediating in their external interactions, and, most counter-intuitively, as contributing to norm change not exclusively through their strength, but also through their weakness.