Since the early 1900s, the major causes of illness and death in the United States have changed from infectious disease to chronic disease. Recognition is growing that nonclinical communityand population-based prevention has a large role in improving the public’s health and well-being. Health risks such as obesity, tobacco use, and low levels of physical activity are the result of a set of complex, interrelated factors that are difficult to untangle and identify. Health behaviors are important (1), but the importance of such factors as the physical, psychosocial, socioeconomic, and legal environments cannot be overstated (2). Community-based, nonclinical prevention policies and wellness strategies account for as much as 80% of the overall health of a population (3), yet assessing the value of community-based prevention remains challenging and complex. How should the value of community-based prevention be assessed? What should be measured? What should be counted, for whom, over what time period, and how?