Hallal and Azevedo are with the post-graduate program in Epidemiology, Federal University of Pelotas, Brazil. Parra and Brownson are with the Prevention Research Center in St. Louis, and the George Warren Brown School of Social Work, Washington University in St. Louis. Pratt is with the Physical Activity and Health Branch, Division of Nutrition, Physical Activity, and Obesity, Centers for Disease Control and Prevention, Atlanta, GA.