Research into Leader-Member Exchange (LMX) theory has been gaining momentum in recent years, with a multitude of studies investigating many aspects of LMX in organizations. Theoretical development in this area also has undergone many refinements, and the current theory is far different from the early Vertical Dyad Linkage (VDL) work. This article uses a levels perspective to trace the development of LMX through four evolutionary stages of theorizing and investigation up to the present. The article also uses a domains perspective to develop a new taxonomy of approaches to leadership, and LMX is discussed within this taxonomy as a relationship-based approach to leadership. Common questions and issues concerning LMX are addressed, and directions for future research are provided.