This study examined the relationships among physiological responses during marital conflict, aggressive behavior, and violence in battering couples. As an index of physiological response, the authors used the male batterer's heart rate reactivity, assessed as the change from an eyes-closed baseline to the first 5 min of their marital conflict interaction. During marital interaction, violent husbands who lowered their heart rates below baseline levels were more verbally aggressive toward their wives. Wives responded to these men with anger, sadness, and defensiveness. The husbands were classified as Type 1 batterers. When compared to the remaining violent husbands (classified as Type 2 batterers), Type 1 men were also more violent toward others (friends, strangers, coworkers, and bosses), had more elevated scales reflecting antisocial behavior and sadistic aggression, and were lower on dependency than Type 2 men. The 2-year followup revealed a separation-divorce rate of 0 for marriages involving Type 1 men and a divorce rate of 27.5% for marriages involving Type 2 men.