Background: Physical activity (PA) declines during early adulthood with higher rates of inactivity in university students. The authors aimed to examine the frequency, intensity, time, type of PA, and the barriers to PA participation in Canadian students during the first year of university. Methods: Questionnaires assessing PA variables were administered to 301 first-year students at the beginning and end of the academic year. Results: PA decreased over a year. Males engaged in more vigorous activity minutes, more strength training, and more organized sports than females (P < .05). Females participated in more fitness activities than males (P < .05). Intramural (noncompetitive and school organized) sport participation remained constant throughout the year. Significant intrapersonal barriers to PA engagement included stress and perceived self-skill; significant interpersonal barriers included lack of friends and peer influence; and significant structural barriers included homework, class schedule, and overcrowded facilities. Conclusion: PA and sport participation declined, and some differences existed between the sexes. Focus should be placed on reducing the barriers that students’ experience that may impact their PA. Interventions/programming to promote different aspects of PA should focus on noncompetitive sport and recreation activities, as well as activities that students can do on their own time. Ensuring the availability of adequate campus facilities is also important.