Meta-analyses of sex differences in physical aggression to heterosexual partners and in its physical consequences are reported. Women were slightly more likely (d = -.05) than men to use one or more act of physical aggression and to use such acts more frequently. Men were more likely (d = .15) to inflict an injury, and overall, 62% of those injured by a partner were women. The findings partially support previous claims that different methods of measurement produce conflicting results, but there was also evidence that the sample was an important moderator of effect size. Continuous models showed that younger aged dating samples and a lower proportion of physically aggressive males predicted effect sizes in the female direction. Analyses were limited by the available database, which is biased toward young dating samples in the United States. Wider variations are discussed in terms of two conflicting norms about physical aggression to partners that operate to different degrees in different cultures.