We examined the role of personality (e.g., hypermasculinity, sensation seeking) and physical individual differences (testosterone, physical attractiveness) in predicting university men's (N = 215) number of sexual partners. Significant zero‐order correlations occurred between number of sexual partners and sensation seeking, hypermasculinity, physical attractiveness, and testosterone. In addition, multiple regression analysis revealed significant increases in prediction with an additive combination of these individual differences, and some of these individual differences (e.g., sensation seeking) contributed unique variation to the prediction of the number of sexual partners. Finally, principal components analysis revealed a common personality factor labeled Disinhibition that may partly underlie the relationship between some of these individual differences and the number of sexual partners. The results are discussed in relation to recent personality research and recent evolutionary theories of human sexua...