Chapter five explores group behavior in organizations, defining groups as collections of individuals whose interactions influence one another. It categorizes groups into formal (command and task groups) and informal (interest and friendship groups), explains why individuals form groups, and details the stages of group development: mutual acceptance, communication and decision making, motivation and productivity, and control and organization. Additionally, it discusses group characteristics like structure, status, roles, norms, leadership, and cohesiveness, and introduces the concept of groupthink, where a desire for consensus can hinder consideration of alternatives.