Women are surprisingly underrepresented in the chess world, representing less that 5% of registered tournament players worldwide and only 1% of the world's grand masters. In this paper it is argued that gender stereotypes are mainly responsible for the underperformance of women in chess. Forty-two male-female pairs, matched for ability, played two chess games via Internet. When players were unaware of the sex of opponent (control condition), females played approximately as well as males. When the gender stereotype was activated (experimental condition), women showed a drastic performance drop, but only when they were aware that they were playing against a male opponent. When they (falsely) believed to be playing against a woman, they performed as well as their male opponents. In addition, our findings suggest that women show lower chess-specific self-esteem and a weaker promotion focus, which are predictive of poorer chess performance. Copyright # 2007 John Wiley & Sons, Ltd.Chess is not only one of the oldest games but it is also, by many, considered the ultimate intellectual sport. Although chess is an intellectual pursuit not requiring physical strength, women are generally considered inferior and they represent less than 5% of registered tournament players worldwide. Currently, the best female player, Judit Polgar, is placed in position 17 of the FIDE ranking (Federation Internationale des Echecs, 2006) and she is also the only woman among the top 100 players of the world. Thus, women seem to be underrepresented as well as underperforming. 1 Why should this be the case? A first step to understand gender differences in chess is to ask what characteristics are predictive of success and whether these characteristics are less common in females. We will only consider general cognitive and motivational factors here and ignore the specific tactical and strategic skills that develop as a function of chess training, including the striking ability of expert chess players to quickly capture the gist of highly complex chess positions (de Groot & Gobet, 1996; Ross, 2006).European Journal of Social Psychology Eur. J. Soc. Psychol. 38, 231-245 (2008) Charness and Gerchak (1996) have argued that women's underrepresentation among top ranks is simply a function of relative participation rates, since extreme scores tend to increase disproportionally as population size increases.