The study of homicide and other violent behavior is becoming increasingly specialized, and researchers have focused on such topics as spousal homicide, child abuse, and violence between strangers. The authors believe, however, that a narrow focus on specific forms of violence may inhibit the formulation of general theories of interpersonal violence. They propose formal models of the effects of gender and intimacy on homicide. For the most part, evidence supports the Gender Differences Model over other models. The probability of victim physical attack can be predicted simply on the basis of main effects of offender and victim gender, and the relationship between the victim and the offender is irrelevant. The tendency for women to kill their partners in response to an immediate violent provocation reflects the fact that they are women and their partners are men, and that men are more violent than women. The authors conclude important differences in patterns of homicide involving female and male partners reflect the powerful relationship between gender and violence. Appendixes contain additional data on the study of the effects of gender and intimacy. 28 references and 5 tables