This study examined cross-cultural sex and gender differences in achievement motivation. In contrast to the common intuition that collectivist societies show greater levels of sex differentiation than individualistic societies, we predicted that sex differences would be greater in individualistic countries. Study 1 found partial support for this prediction across five countries. Also, this study demonstrated that regardless of the country's level of individualism, gender roles are better predictors of achievement motivation than sex. Using representative data from 37 countries, Study 2 found individualism to be related to greater sex differences in achievement motivation. The findings of these two studies contributed to the growing cross-cultural literature on sex and gender demonstrating that men and women seem to differ more in individualist societies.