||Previous research examining the impact of a romantic breakup on individuals' self-concepts indicates that individuals experience a number of detrimental outcomes regarding their sense of who they are. In addition to dyadic relationships, group memberships also have a powerful influence on individuals' self-concepts. The present study tested whether a threat to a group membership would also evoke changes to individuals' self-concepts. Eighty-five upperclassmen reported how strongly identified they felt with their university as a group. Students were then randomly assigned to experience a threat to their university group membership or a preservation and continuation of that group membership. Results indicated that strongly identified participants who experienced the threat to their group membership showed evidence of reduced self-concept clarity, greater self-concept change, and reduced self-esteem in comparison to students who were weakly identified with the group or did not experience the threat. Implications and directions for future research are discussed.