Membership Matters

A framework for integrating diverse aspects of membership dynamics is outlined, and 10 propositions about membership change and its impact on group structure, process, and performance are presented. Data from a longitudinal study of 22 small (3-to 5-person) groups are used to test some of the propositions. Groups that had an experimentally imposed temporary member (a "guest") and groups with spontaneous membership changes, such as absences, performed better on a task requiring reflection about the group's internal processes than did groups with a stable membership. No such effect wasfoundfor performance on other types of tasks. Some evidence was found for higher cohesiveness among groups with changing attendance compared to groups with greaterweek-to-weekstability. However, groups with a history of member change felt less positive about their groups when a guest replaced a regular member than did more stable groups. Groups with guests reported spending more time on task and less time dealing with conflict than did groups with no guests. Similar effects werefoundfor groups meetingface-to-face and via computers. Implications for work groups and other types of small groups are discussed