Cohesion and membership duration: Linking groups, relations and individuals in an ecology of affiliation

The study of group cohesion has a rich but confused history. Cohesion was originally a group-level concept, referring to the degree to which a group tends to maintain a stable, committed membership over time. As a largely psychological literature developed, however, an increasing focus on interpersonal attraction translated into the individual-level study of liking and interdependence. Recent advances in both psychology (Hogg, 1992) and sociology (Lawler & Yoon, 1996) usefully reassert the central role of social structure in determining a group's cohesiveness. We argue, however, that current approaches have enriched our understanding of intraindividual processing at the expense of the sociological understanding of the coevolution of groups and their members' networks within a larger community structure. We review the literature on this ecology of affiliation to draw inferences about both group cohesiveness and members' attachment to the group. Then we extend a theoretical simulation of these ecological processes to show how system-level properties of communities can influence group cohesion.