Objective: The purpose of this cross-sectional investigation was to examine (1) gender differences in osteoporosis-related knowledge and beliefs and (2) if these beliefs could predict vigorous physical activity behavior in university students. Participants: Male (n = 176) and female (n = 351) university students participated in the study. Methods: Participants completed self-report measures of osteoporosis knowledge and health beliefs and vigorous physical activity. Results: Regardless of gender, osteoporosis knowledge was relatively poor. Women reported higher knowledge, perceived susceptibility, perceived severity, and calcium barriers, and lower exercise self-efficacy than men. Regression analyses showed that for women, perceived susceptibility, health motivation, and exercise self-efficacy predicted vigorous physical activity, whereas for men, exercise barriers was the only predictor. Conclusions: Gender differences in osteoporosis health beliefs appear to be greater in older adults than college-aged students. Interventions designed to increase vigorous physical activity may want to target different beliefs for men and women. (Contains 1 note and 2 tables.)