We report the results of ultimatum game experiments designed to test for differences in the behavior of women and men. Women's proposals are on average more generous than men's, regardless of the sex of the partner, and women respondents are more likely to accept an offer of a given amount. A given offer is more likely to be accepted if it comes from a woman; we term this result chivalry. Women paired with women almost never fail to reach an agreement; we term this result solidarity. Age, earnings, and race also significantly affect proposals and the rates of rejection.