How to achieve effective board monitoring is a classic puzzle in corporate governance. Yet the increasing attention to executive traits in predicting board monitoring has let scholars and practitioners assume that dominant CEOs clearly represent one factor that threatens this outcome. Drawing from psychological and management insights, we challenge this assumption. We propose that in the increasingly common non-duality setting (i.e., separation of CEO and chair position) CEO dominance may in fact increase board monitoring and that this relation critically depends on the dominance of the boards’ chair. In an experimental study among 81 non-executive directors and a survey study conducted among non-executive directors, chairs of non-executive boards, and CEOs from 120 Dutch organizations, we find large support for the positive effect of CEO dominance on board monitoring and full support for the interaction effect of CEO and chair dominance. There was a positive relationship between CEO dominance and monitoring in the non-duality setting when the chair was also dominant, but this effect became non-significant when the chair was not dominant. Among other implications, the results highlight the importance of nuancing the effects of dominance for different governance contexts, and further examining the important role of board chairs.