The influence of mitigating circumstances on family reactions to physi
cal aggression was investigated. 40 families, each with a 2- and a 4-y
ear-old child, were observed during home interactions, and parents' an
d older children's beliefs concerning mitigation were also assessed. A
lthough parents considered sibling physical aggression to be a serious
transgression, they believed that mitigated aggression of both of the
ir children was more excusable and they intervened less often to prohi
bit mitigated than nonmitigated aggression, even when the aggression w
as severe. Older children also believed that mitigated aggression dese
rved less punishment. Provocation, reciprocity, and lack of aggressive
intent occurred as mitigating circumstances in the observations. When
family members' reactions to these individual circumstances were exam
ined, discrepancies arose in judgments of which specific mitigations j
ustified aggression. These findings were discussed in terms of the cla
rity of a parent's message, children's appraisals of it, differing con
flict roles, and society's impact.