Organizational research on the dark triad has, so far, focused on individual differences in employees’ stable tendencies to act in manipulative, grandiose, or callous ways (i.e., dark triad traits). Research on momentary expressions of Machiavellianism, narcissism, and psychopathy (i.e., dark triad states) and the work situations that may trigger them is still in its infancy. Based on the conservation of resources theory, we hypothesized that daily role ambiguity and role conflict deplete employees’ daily self-control resources which, in turn, is related to the daily expression of dark triad states. To test our hypotheses, we conducted two daily diary studies across 5 and 10 workdays. Consistent with expectations, on days when employees experienced more role conflict than usual, they were more likely to express their darker side of personality. In contrast, hypotheses about the detrimental effects of daily role ambiguity and the mediating role of daily self-control depletion were not supported.