We examined the relations between emotionality, emotion processing, and aggression in 182 first- and second-grade children. Consistent with Tomkins' and Izard's theoretical predictions, emotionality correlated with emotion processing. In particular, the happiness component of emotionality correlated with emotion attribution accuracy and empathy, the anger component correlated with anger attribution bias and empathy, and the fear component correlated with fear attribution bias. Multiple emotion processing deficits-including emotion attribution accuracy, anger attribution bias, and self-report of empathy-placed children at risk for heightened levels of teacher-reported aggression. Mediational analyses revealed that an emotion processing risk index fit a model of significant partial mediation between happiness and aggression but not between anger and aggression. The results suggest the multifaceted manner in which children's emotion experiences may influence the development of aggressive tendencies.