Objective: To examine the relations of sex, exercise self-efficacy, outcome expectations, and social support with meeting physical activity guidelines (PAGs). Participants: Three hundred ninety-six college students participated in this study in the summer 2013. Methods: Students completed online questionnaires that assessed physical activity behaviors and psychosocial factors (i.e., self-efficacy, outcome expectancies, and social support). Students' physical activity profile was categorized as meeting no PAGs, meeting aerobic PAGs only, meeting muscle-strengthening PAGs only, or meeting both PAGs. Results: A multinomial logistic regression revealed that students' sex and psychosocial factors significantly affected the odds of meeting any and all PAGs. Sex significantly moderated the relationship between outcome expectancy and meeting aerobic PAGs and between outcome expectancy meeting muscle-strengthening PAGs. Conclusions: Results indicate that interventions designed to increase psychosocial factors may increase the likelihood of students meeting any and all PAGs. Social support may be especially beneficial for increasing muscle-strengthening activity.