Physical inactivity has been identified as a major health risk factor, both in the U.S. as well as internationally. Physical education programs have been identified as a critical aspect of the effort to encourage individuals to adopt and maintain healthy active lifestyles, and it is important to develop strategies that can be used in educational programs to accomplish that goal. Many factors such as culture, gender, and levels of self-regulation are influential in the decisions individuals make regarding their involvement in physical activity. If physical educators are to design motivational climates that will foster the development of active lifestyles, we must learn more about how social factors affect motives to engage in physical activity, and that was the purpose of this study. Participants were 902 (327 from the US, 304 from Italy, and 271 from China; 521 females and 381 males) individuals ranging in age from 12 to 22. They completed a survey consisting of three sections. The first section, adapted from previous work, provided demographic information and was designed to gather self-report data about levels of physical activity. The second section, also adopted from previous work, asked participants to rank the importance of 25 motives for participation in physical activity. The third section was the Exercise Self-Regulation Questionnaire. The survey was developed in English, and translated into Italian and Chinese by the researchers. Data were analyzed using 2 (gender) X 3 (culture) multivariate analyses of variance (MANOVAs) with univariate follow-ups. Results indicated that self- reported participation patterns, motives to participate in physical activity, and levels of self- regulation in exercise varied according to gender and culture. All participants rated improving health and fitness as an important motive for exercise. Males reported being more active than females, but females were more self-determined in their exercise regulation. Males tended to rate gaining status as a more important motive than females. Participants from the U.S. reported exercising more regularly than those from Italy and China. Individuals from both the U.S. and Italy were more self-determined than those from China. Participants from China and the U.S. rated improving physical fitness as the most important reason to exercise, while for Italians having fun was ranked as most important. The results suggest that culture, gender, and self-regulation are important factors to consider in designing programs to foster active engagement in physical activity.Keyword(s): gender issues, physical activity, research