["Journal of Organizational Behavior, EarlyView. ", "\nABSTRACT\nWe study the phenomenon of ambivalence to lead, characterized as leaders' experience of mixed feelings (positive and negative) toward their leadership position. We do so by integrating the beneficial role of dualities with the affect‐as‐information theory. Our model shows that the duality involved in ambivalence to lead activates leaders' integrative complexity—the ability to identify and integrate different perspectives on the same subject—which in turn increases their effectiveness as leaders. This positive effect is altered by the leader's perceptions of structural dynamics of the workplace: organic vs. mechanistic. The former allows for greater individual discretion and action than the latter, facilitating an environment in which ambivalence to lead can further activate leader integrative complexity and, in turn, leader effectiveness. To examine our model, we conducted two studies using different research designs (experiment and field) and various organizational settings from three data sources (managers, their supervisors, and objective raters) at three time points. The findings provide substantial support for our thesis, demonstrating that ambivalence to lead enhances the effectiveness of leaders (through leader integrative complexity) and that this indirect positive effect is stronger (vs. weaker) under an organic (vs. mechanistic) structure.\n"]