This paper examines why group norms are enforced and how group norms develop. It is argued here that groups are likely to bring under normative control only those behaviors that ensure group survival, increase the predictability of group members' behavior, avoid embarrassing interpersonal situations, or give expression to the group's central values.Group norms develop through explicit statements by supervisors or co-workers, critical events in the group's history, primacy, or carry-over behaviors from past situations.