Presents a model that describes the reciprocal influence of disruptions in parent discipline practices on irritable exchanges between the target child and other family members. Disrupted parent discipline and irritable microsocial exchanges within the family were hypothesized to provide a basic training for aggression that generalizes to other settings such that the child is identified by peers, teachers, and parents as physically aggressive. Physical fighting was thought to lead to rejection by the normal peer group, which was hypothesized to feed back to further exacerbate fighting. Multilevel assessments including interview, questionnaires, laboratory studies, and home observations were carried out with the families of 91 4th-, 7th-, and 10th-grade boys. Nine indicators from the assessment battery were used to define the constructs of inept parental discipline, negative microsocial exchanges, physical fighting, and poor peer relations. Structural equations were used to describe the relations among the constructs. Findings support the hypothesis that under certain circumstances, family interaction may serve as basic training for aggression. Interactions with siblings in the home seemed to have a pivotal role in subsequent aggressive behavior.