This study examines the relationships between organizational citizenship behaviors (OCBs) and knowledge sharing using gender as a moderator. In the proposed model, five components of OCBs-altruism, courtesy, conscientiousness, sportsmanship, and civic virtue-influence knowledge sharing. Gender stereotypes have a moderating effect on each path and a main effect on each antecedent. These moderating effects are simultaneously examined using data obtained from employees at various companies who attend evening college classes for advanced study in Taiwan. A moderating test reveals that the influence of altruism on knowledge sharing is stronger for women than for men, while the influences of courtesy and sportsmanship on knowledge sharing are stronger for men than for women. Lastly, the influences of conscientiousness and civic virtue on knowledge sharing are similar between women and men. Implications of empirical findings are also discussed.