The primary objective was to examine severity and gender differences in reports of the worst episode of marital aggression using a functional analysis conceptualization. That is, current stressors, setting events, outcome and function of aggressive behavior, and victimization experiences were evaluated within specific episodes. Sixty-two couples who presented for marital treatment over a 3-year period and also reported at least one episode of physical aggression in the past year participated in the study. In most cases, marital aggression appeared to reflect an outgrowth of conflict between both partners. However, wives consistently reported that their aggressive husbands engaged in more psychological coercion and aggression than they did as the marital conflict escalated to physical violence. Further, there was a tendency for wives to use severe physical aggression in self-defense more often than husbands. The authors conclude that marital violence may result from conflict between both partners in which each actively contributes, but not necessarily symmetrically, to the escalation of violence. Appendixes contain additional information on the study's coding system and aggression and victimization vignettes. 41 references and 9 tables