ObjectiveResearch on the role of affect in childhood aggression motives has largely focused on domain-level affective traits. Lower-order affective facets may show more distinct relationships with instrumental and reactive aggression - at both the variable and individual levels - and offer unique insights into whether and how several forms of affect are involved in aggression motives.MethodCaregivers (98% mothers) of 342 children (Mage = 9.81 years, 182 girls, 31% White) reported on children's aggression and affect-relevant personality traits, personality pathology, and callous-unemotional traits.ResultsBoth reactive and instrumental aggressions were characterized by higher levels of trait irritability, fear, withdrawal, sadness, and callous-unemotional traits in zero-order analyses. Instrumental aggression was characterized by low trait positive emotions. Reactive aggression was uniquely associated with irritability, fear, withdrawal, and sadness, whereas instrumental aggression was uniquely associated with callous-unemotional traits and (low) positive emotions. Groups identified by latent profile analyses were differentiated only by aggression severity.ConclusionsThe findings support both the similarity and distinction of reactive and instrumental aggression vis-a-vis their affective phenomenology. Consistent with existing theories, reactive aggression was linked to multiple forms of negative emotionality, whereas instrumental aggression was linked to higher levels of callous-unemotional traits. In a novel finding, instrumental aggression was uniquely characterized by lower positive emotions. The findings highlight the utility of pre-registered approaches employing comprehensive personality-based affective frameworks to organize and understand similarities and differences between aggression functions.