| Period | Leadership theory | Theme of research |
| 1940s to 1950s | Trait theory | Focuses on the character trait |
| 1940s to 1960s | Behavior theory | Focuses on behavior style of leaders |
| 1960s to 1980s | Contingency theory | Consider situational factors |
| Since the 1980s | New theory | Emphasizing the leader’s vision and mission as well as the influence on members |