Theories of leadership have traditionally focused on leadership traits, styles, and situational factors that influence leader behaviors. We propose that The Four Umpires Model described herein, which examines how four leadership types view reality and perception, provides a useful example of an effective steward leader. We use the Five Beliefs Model identified by Edgar Schein and Peter Senge to frame the implicit assumptions underlying the core beliefs and mental models of each of the four umpires. We suggest that the stewardship (...) model of Umpire Number Four, the Facilitating Idealist, is the best model for leadership of the four umpires described. In our review of the Four Umpires Model we also explain why it is importance for every leader to thoughtfully assess the assumptions that form the ethical basis for leadership decisions and actions. (shrink)