Objectives: The present study aims to explore the impact of impulsivity and self-serving cognitive distortions on relational aggression in peer relationships and romantic relationships. Method: The present study asked 128 participants aged between 18 and 77 to complete a survey which assessed their impulsivity, self-serving cognitive distortions, peer-relational aggression, and romantic-relational aggression. Results: The hierarchical multiple regression analyses demonstrated that impulsivity and self-serving cognitive distortions together predicted romantic-relational aggression. The hierarchical multiple regression also found that impulsivity and the minimising/mislabelling cognitive distortion individually contributed to the prediction of romantic-relational aggression. Impulsivity and self-serving cognitive distortions did not, however, predict peer-relational aggression individually or as a group. Conclusion: The findings suggest individuals who are highly impulsive and who possess the minimising/mislabelling cognitive distortion are predicted to perpetrate relational aggression. The greater the amount of individuals who understand the possible consequences of these factors and understand the severe impact their relational aggression can have on their partners, the more likely the perpetration of relational aggression will be reduced.