The purpose of the present study was to provide evidence of discriminant validity for the aberrant self-promotion construct proposed by Gustafson and Ritzer (1994a). The study attempted to differentiate the aberrant self-promotion construct from the Machiavellianism construct proposed by Christie (1970a). The aberrant self-promoter (ASP) has been conceptualized as exhibiting high self-esteem, low social desirability, and a high degree of antisocial behavior. In contrast, the Machiavellian has been conceptualized as an individual who is coldly rational in determining his or her actions and who is adept at engaging in manipulation to achieve a desired end. It was proposed in the present study that although both the ASP and the Machiavellian may be characterized by high narcissism, high self-esteem, and low social desirability, the Machiavellian does not exhibit the antisocial behavior that is a key component of the ASP pattern. The proposed differentiation, based on 28 undergraduate ASPs and 19 undergraduate Machiavellians, involved a structured interview and a prisoner's dilemma game. The results from the interview showed that the ASPs scored significantly higher on the total score, as well as on the subscore for a narcissism-related factor and on the subscore for an antisocial behavior factor. The prisoner's dilemma results, however, revealed no significant differences between the ASPs and Machs. Discussion focused on the insufficient salience of the prisoner's dilemma experimental situation and on the research and organizational implications of the ASP/Machiavellian differentiation supported by the interview.