In the Leader-Member Exchange (LMX) theory of leadership, the quality of the exchange relationship between a leader and a particular member of a work unit, team or organization is the basic unit of analysis (dyad). In this article, we try to answer the question whether research on the various aspects of the exchange processes between leaders and their subordinates is consistent with the theoretical underpinnings of LMX theory. Our focus is on the similarities and differences between the theoretical assumptions of LMX theory and the way the core concepts are elaborated in empirical studies. Although LMX theory has resulted in a number of useful accomplishments, both theoretical and practical, it still faces a number of challenges. The main challenges are to carry out a thorough and consistent refinement of the measuring instruments used, and to gain more insight into the mutual behaviours, attributions, and evaluations which facilitate or inhibit the development of high-quality working relationships.