Correlational analyses reveal several findings: (1) significant relations between parental hostility and child aggression both concurrently and across time and (2) a relationship between child aggression and future aggression in children. Child aggression and parental hostility also elicited each other, thus providing evidence for family socialization as an interactive process. Parental hostility has long been hypothesized to be a crucial contributor to children’s aggression. The findings suggest that future studies should include additional variables, such as sex, age, and child personality. This study was interested in whether the bidirectional relationship between hostile parenting and children’s aggression would mediate future aggression in children. The aim of this study was to examine the concurrent and across-time relations between mother/father hostility and previous and future aggression in children. The sample, consisting of 523 primary and secondary school children, was derived from a longitudinal study conducted over 3 years. Table, figures, and references