In the late 1980s/early 1990s the concept of leadership was introduced in the study of international regimes to describe the role negotiating parties sometimes would take on to craft agreement. The concept seemed to grasp an essential feature of multilateral cooperative efforts: that parties can be differentiated by the extent to which they are capable of, and willing to, take on a particular responsibility of guiding other parties in directions that could lead to joint solutions. The concept of leadership has only to a small extent been subjected to critical analytical and conceptual discussion. In this article we revisit the concept by asking: What are the characteristic features of leadership in international negotiations? Our analysis shows that current conceptualizations of leadership are associated with significant ambiguities that make it hard to distinguish leadership behavior from other types of bargaining behavior and that these problems are reproduced in empirical identifications of this mode of bargaining behavior.