Objective: The purpose of this study was to inform the ongoing quest for efficacious treatment of domestically violent women by (a) describing their representation in cases of intimate partner homicide over the period of 1985-1999 in Houston, Texas, and (b) by utilizing a measure known as the spousal sex ratio of killing (SROK), determining variation in this female offending by race/ethnicity and whether the relationship was registered or "defacto." Method: Secondary data from the Houston police department homicide division murder logs and the U.S. Bureau of the Census were analyzed to determine the incidence and proportion of women's perpetration of intimate partner homicide. Results: Throughout the fifteen-year period of this study, women were over 40 percent of the offenders in lethal domestic assaults. Both victims and offenders in these intimate partner incidents were disproportionately Black. When comparing the sex ratios of killing by racial/ethnic subgroups, Black women were equally (or more) likely than Black men to be the perpetrators of intimate domestic homicide. Among non-Hispanic Whites (including Asians, others), there were 63 female intimate partner homicide offenders for every 100 male offenders. Within the small number of cases involving Hispanic couples, women were much more likely to be the aggressors in intimate partner homicide in the latter time period of this investigation. For both Blacks and Whites women were more likely to be the perpetrators in non-marital dyads. Conclusion: Implications of these findings for criminal justice and social service practitioners are discussed. (Contains 3 tables and 1 note.)