It is a commonly held stereotype that women show superior performance on tests of social cognition such as face processing and theory of mind (ToM) compared to men. However, such purported differences have not been empirically tested. In this study 40 healthy men and 40 women matched for age and years of education completed a well-known experimental ToM test requiring the attribution of either physical or mental states (Happ's cartoon task). Men showed superior performance compared to women, with a medium effect size, on both the mental state and physical state cartoons. It is suggested that men may use a cognitive systemising strategy during these tasks. The results emphasise the task-specific nature of sex differences in social cognition and necessitate future work to elucidate individual differences at the interface of cognitive and affective processes.