The study found that personality-disordered male batterers in this study were significantly more violent toward their partners and inflicted more injuries than the control group without diagnosed personality disorders. In addition, the violence of men with different personality disorders apparently differed in its function. Within the context of an intimate relationship BPD/comorbid men engaged largely in reactive violence, and ASPD men tended to use violence both proactively and reactively. Perhaps the effectiveness of current batterer treatment programs could be improved by increasing punishment and/or decreasing reinforcers for proactive violent behavior. For batterers prone to reactive violent behavior, treatment might target the management of emotions and stimuli that trigger violent reactions. Since reactive aggression has been found to be more pervasive than proactive aggression, treatments suitable for this type of aggression should be provided for all batterers, while adding interventions for proactive violence as needed. Participants responded to ads in free, local newspapers and flyers that solicited "couples experiencing conflict." The final sample consisted of 124 couples in which at least 1 partner reported some male to female intimate partner violence (IPV) in the past year. Intimate partner violence was measured with the Revised Conflict Tactics Scale. Clinical psychology graduate students administered the structured clinical interview for DSM-IV personality disorders. Women were individually administered a semistructured clinical interview that has been used in previous research (Jacobson et al., 1994). 3 tables, 41 references, and appended violent incident description codes