Obesity is an epidemic that likely will worsen without substantive changes to the current environment. Although treatment of the individual has conventionally been the focus of the obesity field, prevention using a public health model will be essential for making progress on a population level. There are encouraging signs that communities across the country are acknowledging the complex causes of obesity and making impressive reforms to improve their health and that of their children. Public policy changes long have been used to combat infectious and chronic diseases and will be vital in the attempt to reduce the toll of poor diet, physical inactivity, and obesity.