This study tested the theoretical assertion that anger and sympathy would be differentially associated with “hot-blooded” reactive and “cold-blooded” proactive aggression in an ethnically diverse community sample of 4- and 8-year-olds from Canada (N = 300; n = 150 in each age group; 50% female). We conducted structured interviews with children to elicit their self-reported anger in response to social conflicts (anger reactivity), ability to effectively manage feelings of frustration (anger regulation), and the degree to which they felt concern for others in need (sympathy). Caregivers completed questionnaires assessing the degree to which children engaged in reactive and proactive overt aggression. Across ages, dysregulated anger was more strongly associated with reactive aggression, whereas lower sympathy was more strongly linked to proactive aggression. Anger reactivity did not predict children’s aggressive behavior, with one exception: lower anger reactivity in 8-year-old males was associated with higher levels of proactive aggression. These findings support the hypotheses that anger and sympathy are differentially involved in reactive and proactive aggression, and that these distinct affective correlates are evident by the preschool years.