Physicians are often asked to assume leadership roles in their practices, hospitals, and academic departments. These positions can be excellent leverage points for improvement of health care quality. To make optimal use of these opportunities, physicians must learn how to lead. This paper is intended to be a primer for physicians who are asked to lead and want to learn how to lead well. A body of knowledge that physician-leaders should acquire is described, and case examples are used to address such topics as the nature of leadership, the relation between leadership and management, and ways in which physicians might approach a new leadership assignment. Guidelines for physicians who must play the role of followers are offered, and challenges that physicians who lead other physicians may face are described.