Previous research suggests that reactive and proactive aggression likely have distinct underlying mechanisms that uniquely contribute to the perpetration of each as a result of faulty cognitive and emotional processes. Still, very little work has examined the association of the functions of relational aggression with emotion dysregulation and hostile attribution biases. In addition, it is important to examine relational aggression in its pure and co-occurring functions given that past work finds reactive and proactive aggression to occur both jointly and distinctly. Thus, the current study employed a bifactor model to distinguish between pure reactive, pure proactive, and co-occurring relational aggression in emerging adulthood (N = 647, M age = 19.92, SD = 2.83), a developmental time period for which relational aggression is particularly prominent. To further address gaps in the relational aggression literature, indirect pathway models revealed that relational hostile attribution biases emerged as a concurrent indirect path in the relationship between emotion dysregulation and pure reactive relational aggression. Furthermore, emotion dysregulation was directly positively associated with both pure functions as well as co-occurring relational aggression, and hostile attribution biases for relational provocations were directly associated with both pure functions of relational aggression, though the association was negative for pure proactive and positive for pure reactive relational aggression.Findings highlight the potential influence of emotion dysregulation and attributing hostile intent to social situations on engaging in the different functions of relational aggression.