The relations between reactive aggression, situational cues, and emotion regulation were examined by means of the Pulkkinen Aggression Machine (PAM) task. In the PAM, provocation and response were systematically varied under two conditions: the impulsive aggression condition and the controlled aggression condition. In the impulsive condition, no information about the attacker was provided, while in the controlled condition the attackers were specified in terms of sex, age, and physical strength. The task was administered to 109 children aged 8 to 13 years. Boys (n = 61) and girls (n = 48), as well as subgroups of Adjusted (n = 67) and Maladjusted (n = 26) children were compared. The results confirmed earlier findings showing that there is a strong relationship between attack and response intensity. However, this relationship was consistently modified by the effects of situation and personality-related variables. This meant that, while for the impulsive condition response intensity was closely tied to stimulus intensity, in the controlled condition this effect was modulated by the characteristics of the opponent: the more equal the opponent the stronger the retaliations displayed. The Maladjusted children reacted more intensively in the impulsive condition and to minor provocation in the controlled condition than the Adjusted children. This suggests that the intensity of the elicited aggression in the Maladjusted group was particularly dependent on contextual rather than internal control. Aggr. Behav. 27:430–445, 2001. © 2001 Wiley-Liss, Inc.