Preferences for conflict and cooperation are systematically different for men and women. At each stage of the escalatory ladder, women prefer more peaceful options. They are less apt to approve of the use of force and the striking of hard bargains internationally, and more apt to approve of substantial concessions to preserve peace. They impose higher audience costs because they are more approving of leaders who simply remain out of conflicts, but they are also more willing to see their leaders back down than engage in wars. Unlike men, most women impose audience costs primarily because a leader behaved aggressively in making a threat, not because the leader endangered the states bargaining reputation through behaving inconsistently. Many of these differences, and possibly all, span time periods and national boundaries. Women have been increasingly incorporated into political decision-making over the last century through suffragist movements, raising the question of whether these changes have had effects on the conflict behavior of nations consistent with their large effects in other areas, such as the size and competencies of governments. We find that the evidence is consistent with the view that the increasing enfranchisement of women, not merely the rise of democracy itself, is the cause of the democratic peace.