One characteristic that all leaders have in common is that they exert influence; thus, a leader is a person who influences the behavior of one or more people. They exert influence by rewarding followers, threatening to punish followers, using their position of power, knowing more than anyone else, or because of their personality. One theory of leadership is that people become leaders because of their personalities and the situations in which they find themselves. These two factors work together.

There are five approaches to leadership. Functional leadership occurs when each member of the group takes on leadership responsibilities depending on the group's task. There are three traditional leadership styles. Authoritarian leaders take charge of a group, especially in situations where the group has little information or experience. Democratic leaders give everyone a chance to participate in decision making, especially in situations where members are equal in status, education, and experience and when there is sufficient time to solve the problem. Laissez-faire leaders do little leading. This kind of leadership works best in self-help groups. Situational leaders can adopt different leadership styles depending on the situation. Using the telling style, they focus more on the task and less on the group. In the selling style, leaders state the problem and decide what to do, then sell the other group members on the idea. Using the participating style, they state the problem but immediately consult with group members. In the delegating style, they hang back and let members plan and execute the job.

A group leader has six responsibilities: to establish procedures, keep the group moving, raise questions, focus on answers, delegate responsibilities, and encourage social interaction.

Participants in group discussion play a variety of roles. Members in task roles focus on getting the job done; members in maintenance roles are concerned with the emotional tone of the group.

Substantive conflict in groups can be disruptive, but it can also help group members come to better decisions. One important task of a group leader is to manage conflict. He or she should determine how serious the conflict is and take one of the following approaches: avoidance, accommodation, competition, collaboration, or compromise.