This study examined the relationship between middle-school aggressive behaviors and young adults' experiences as victims and perpetrators of intimate partner physical violence. As part of the Reach for Health longitudinal study, surveys were conducted with 977 8th graders who were resurveyed as young adults, when lifetime partner violence was assessed. In this economically disadvantaged sample, the prevalence of middle-school aggression and subsequent partner violence are high among both males and females. In middle school, 32% of girls and 42% of boys reported being in a recent fight and 12% of girls and 17% of boys had threatened another with a weapon. By the time they were 19-20 years old, about 35% of females and males reported being the victims of one or more forms of partner violence; 35% of females and 22% of males reported one or more forms of perpetration. Controlling for socio-demographic characteristics, middle-school aggression is a significant risk factor for partner victimization and perpetration. Early aggression remains an independent predictor of partner violence perpetration and victimization for males and perpetration for females when other middle-school risk behaviors and exposures to physical aggression in the childhood home are taken into account. To reduce partner violence through young adulthood, findings suggest the importance of early interventions that help adolescents learn non-violent strategies for resolving conflicts in cross-gender relationships.