This mixed-methods study describes the norms supporting male-to-female and female-to-male dating violence in a diverse sample of ninth graders. The quantitative study, based on student surveys (n = 624), compared norms supporting dating violence by sex, race/ethnicity, and dating status, and it examined the relation between dating violence norms and physical aggression and victimization. The qualitative study, based on 12 focus groups, explored participants' views of dating aggression. Findings revealed more support for female-to-male aggression, greater acceptance of norms supporting dating violence by non-White students, a strong association between norms and physical aggression but only in males, and a high correlation between victimization and perpetration. Participants rejected male-to-female dating aggression because of peer pressure not to hit girls, parents' beliefs that denounce dating violence, the superior physical advantage of boys over girls, and legal consequences. Results highlight the importance of culturally sensitive and gender-specific interventions. (Contains 3 tables.)