It can be useful to classify leadership theories according to the type of variables that are relevant for understanding leadership effectiveness. These variables include the following:

• characteristics of leaders
• characteristics of followers
• characteristics of the situation

Most leadership theories emphasize one category more than the others as the primary basis for explaining effective leadership. Over the past half-century, leader characteristics have been given the greatest emphasis.

Leadership theories are often classified into the following five approaches:

• trait approach—Emphasizes attributes of leaders such as personality, motives, values, and skills.
• behavior approach—Examines how managers cope with demands, constraints, and role conflicts in their jobs.
• power-influence approach—Examines influence processes between leaders and other people. It takes a leader-centered perspective with an implicit assumption that causality is unidirectional (leaders act and followers react).
• situational approach—Emphasizes the importance of contextual factors that influence leadership processes. Major situational variables include the characteristics of followers, the nature of the work performed by the leader’s unit, the type of organization, and the nature of the external environment.
• integrative approach—Includes two or more types of leadership variables in the same study.

Another way to classify leadership theories is in terms of the “levels of conceptualization,” or the type of constructs used to describe leaders and their influence on others. Leadership can be described as the following:

• an intra-individual process
• a dyadic process
• a group process
• an organizational process

The levels can be viewed as a hierarchy, as depicted in the figure below:

The important variables in play at different levels of conceptualization for leadership are shown in the table below.