A total of 696 interviews were conducted over 6 collection periods during the years 1999-2001. An interview instrument developed specifically for this project was developed. Between 28.8 percent and 38.3 percent of domestic violence cases were committed while the abuser was taking a psychoactive substance prior to the episode. Verification of drug use during an incident of domestic violence was possible for only 59 cases. For the arrestees, multiple drug use was most often associated with incidents of domestic violence, with marijuana being the most frequently named drug. A history of a high rate of mutual abuse between intimates was reported. Drug and/or alcohol use prior to the most recent incident of domestic violence increased the likelihood that the violence would be severe. Females were more likely to be the victims of severe domestic violence. Variations in levels of aggressive behavior as measured by the severity of the domestic violence act, using the modified Conflict Tactic Scale, were attributed to a history of family violence in the family of orientation, as well as drug/alcohol use prior to the most recent incident of domestic violence. The presence of a psychotic substance in connection with domestic violence increased the likelihood that the act would be severe. Due to limitations of this study, the researchers recommend that the dissemination of its findings be restricted to practitioners and policymakers. The findings suggest the need to examine treatment methodologies to ensure an integrated system that provides appropriate treatment of individuals involved in both substance abuse and domestic violence. 7 tables, 81-item bibliography, and appended interview instrument and codes