Narcissism—a personality trait prevalent in organizations—is characterized by grandiosity, entitlement, and a tendency to engage in unethical workplace behaviors. However, research has often treated narcissism as unidimensional, overlooking its subtypes: grandiose and vulnerable. The current research bridges this gap by examining the relationships between grandiose/vulnerable narcissism and self-interested unethical behavior as well as the mechanisms underlying these effects. Hypotheses were tested in a sample of full-time working adults (N = 176), using a moderation-of-process experimental design with a behavioral measure of self-interested unethical behavior. The findings indicated that grandiose narcissism was positively associated with self-interested unethical behavior and this effect was mediated by heightened self-interest and impulsivity. Targeted interventions deactivating these mechanisms effectively weakened the relationship between grandiose narcissism and self-interested unethical behavior, highlighting the potential for subtype-specific approaches to mitigating ethical misconduct. In contrast, vulnerable narcissism was not significantly associated with self-interested unethical behavior. Theoretically, our findings advance the organizational behavior literature by emphasizing the heterogeneity of narcissism and its relevance in unethical workplace behavior, providing causal evidence for the mediating roles of self-interest and impulsivity, and offering insights into the socioanalytic and self-regulatory nature underlying narcissistic behavior. Practically, our findings provide a foundation for the development of interventions aimed at reducing self-interested unethical workplace behaviors.
