This study examines the relationship between prior parental physical punishment and future aggressive behavior in children, as well as the mediating role of anxious and avoidant attachment in the relationships. Using an 8-month longitudinal study design, data were collected at 3 waves, with a 4-month interval across waves. 762 students participated at Wave 1 (Mage = 12.1 (SD = 1.14), 48% female). The number decreased to 484 at Wave 2 and 368 at Wave 3. The Harsh Punishment was used to measure physical punishment at Wave 1, the Experiences of Close Relationship (short version) was used to measure avoidant and anxious attachment at Wave 2, and the Aggression Scale was used to measure aggressive behavior at Wave 3. Results showed that parents' physical punishment behavior significantly predicted the development of future aggressive behavior, and that anxious attachment played a mediation role in the relationship. These findings suggest the urgent need for developing measures to treat physical punishment and parent-child attachment as a solution to effectively address the prevalence of school violence in Vietnam.