According to cultural capital theory, middle-class families cultivate their childrens cultural capital to promote their social mobility through success in school. We advance the explanatory power of the theory by measuring cultural capital in terms of mastery rather than participation or attendance using data on more than 12 thousand schools about their success in interscholastic athletics. We find that predominantly middle-class schools win more contests and by larger margins than economically integrated and predominantly working-class schools. The margins of victory become larger as the social class differences between the opposing schools grows. We also find evidence consistent with resistance theory because predominantly working class schools also experience success, albeit relatively modest. Our findings have implications for cultural capital theory, resistance theory, and our methods for studying them. By measuring mastery of cultural capital, we identify large social class differences among participants in cultural capital and a close alignment between middle-class culture and school culture.