We all think we understand the formula for keeping healthy-- eat right, exercise, don’t smoke, skip dessert. But that picture is vastly incomplete, perhaps fatally so. While our individual health is highly dependent on our daily behaviors, it may be even more strongly influenced by the social and environmental conditions in which we live. Smith, a prestigious doctor, argues that the future of our health, and our healthcare system, depends on growing and supporting a new generation of healthcare practitioners who look upriver at the source of our health problems, rather than simply opting for quick-hit symptomatic relief. These “Upstreamists,” as he calls them, are practitioners on the frontlines of health who see that health (like sickness) is more than a chemical equation that can be balanced with pills and procedures administered within clinic walls. They see, rather, that health begins in our everyday lives, in the places where we live, work, eat and play. Upstreamists — who may be doctors, nurses or other clinicians — know that asthma can start in the air around us, or from the mold in the walls of our homes. They understand that obesity, diabetes and heart disease partly originate in our busy modern schedules, in the unhealthy food choices available in our stores and even in the way our neighborhoods are designed. They believe that depression, anxiety and high blood pressure can arise from chronically stressful conditions at work and home. And, just as important, these caregivers understand how to translate this knowledge into meaningful action.