Narcissism plays a central role among the personality traits that lead to problems in the workplace and beyond and its complexity has fascinated researchers for decades. Although mostly studied as a one-dimensional trait, narcissism has in fact different facets, such as grandiosity, authority and entitlement. Its association with self-interest is well-established conceptually and could be particularly damaging to organizations, despite some research attesting to positive effects of narcissism. Empirically disentangling the relationship of different facets and situational cues will advance our understanding of narcissism and self-interested behavior. Thus, we contacted employees (N = 370) via a panel firm to assess personality traits and, two weeks later, measures for self-interested behavior based on two different situations that may occur in the workplace. Our results suggest that trait narcissism is not related to self-interested behavior and may, depending on the situation, even be a negative predictor. Exploitative entitlement predicted self-interested behavior, but only in a scenario that was somewhat suggestive of an opportunity to take an unduly large reward for oneself. We interpret our findings in terms of trait activation and discus potential alternative explanations, as well as conceptual difficulties of the concept self-interest.