Research in social sciences other than economics indicates substantial differences in behaviour between men and women. The general conclusion drawn from this work is that women will be more socially-orientated (sel¯ess), and men more individually-orientated (sel®sh). This paper reports the results of a double-anonymous dictator experiment designed to permit the emergence of basic gender differences in economic behaviour. Our results are intended to provide a baseline for further research. We ®nd that women, on average, donate twice as much as men to their anonymous partners when any factors that might confound cooperation are eliminated. For example, in psychology, studies in moral behaviour, game playing, and helping behaviour ®nd consistent sex differences (Eagly and Crowley, 1986;Gilligan, 1982;Uesugi and Vinacke, 1963;and Vinacke, 1959). In sociology, studies ®nd sex differences in criminality and illicit and prescribed drug use (Cooperstock and Parnell, 1982;Gottfredson and Hirschi, 1990;Kandel and Logan, 1984;and Wilson and Herrnstein, 1985). Studies in political science report the development of a`gender-gap' in political behaviour. Since the 1980 elections, women, relative to men, have shown a bias towards Democratic candidates. Women's voting behaviour is driven more by social issues than that of men (Baxter and Lansing, 1983;Christy, 1987;Goertzel, 1983;and Moore, 1996).2 Related research on the role of fairness reveals behaviour that seems inconsistent with standard game theory (Hoffman et al. 1994;Forsythe et al. 1994;Roth, 1995). Theoretical developments have followed suit, incorporating a preference for fairness into agents' utility functions (Young, 1994;Rabin, 1993).
