Drawing on the literature of over 600 research projects, this text sets out to answer questions such as what a group is and how it functions in society, why people join groups, what makes a group cohesive, who becomes a leader, and what exactly status or authority is. Although problem-solving, decision-making, performance-producing and judgment-rendering typically define the goals of task groups, the book focuses on the actual processes that take place in these groups. It also looks at a variety of issues involving groups, such as minority influence, social loafing, choice shifts, group polarization, jury decision-making, social-decision schemes, and group thinking.