FN ISI Export Format VR 1.0 PT J TI The X-factor: On the relevance of implicit leadership and followership theories for leader–member exchange agreement AF van Gils, Suzanne Van Quaquebeke, Niels van Knippenberg, Daan AU van Gils, S Van Quaquebeke, N van Knippenberg, D SO European Journal of Work and Organizational Psychology SN 1359-432X VL 19 BP 333 EP 363 PY 2010 AB Although leader–member exchange (LMX) research shows that leaders engage in different kinds of relationships with different followers, it remains somewhat of an enigma why one and the same relationship is often rated differently by a leader and the respective follower. We seek to fill that conceptual void by explaining when and why such LMX disagreement is likely to occur. To do so, we reconsider antecedents of LMX quality perceptions and outline how each party's LMX quality perception is primarily dependent on the perceived contributions of the other party, moderated by perceived own contributions. We then integrate the notion of Implicit Leadership and Followership Theories (ILTs and IFTs) to argue that the currencies of contributions differ between leaders and followers. This dyadic model sets the stage to explain that LMX disagreement can stem from (1) differences in both parties' ILTs as well as both parties' IFTs, but also from (2) differences in perceptions of own and other's behaviour. We conclude by discussing communication as a means of overcoming LMX disagreement and propose an array of potential studies along the lines of our conceptualization. DI 10.1080/13594320902978458 ER