Examined the complex interplay among emotion, attention, and aggression in a sample of 141 maltreated and 87 non-maltreated impoverished, inner-city children. Data were collected during a summer day camp, which provided an ecologically valid setting for studying children's behavior in social contexts. Maltreated children were more likely than non-maltreated children to be aggressive, with findings suggesting that physically abused children were at heightened risk for reactive aggression. Maltreated children also evidenced attention deficits, and subclinical or nonpathological dissociation was more likely among children who had experienced physical or sexual abuse. A history of abuse also predicted emotion dysregulation, affective lability/negativity, and socially inappropriate emotion expressions. This emotion dysregulation, fostered by poor attention modulation, was a mechanism of the effects of maltreatment on reactive aggression.