Unprecedented increases in obesity in the United States have contributed to greater prevalence of diseases, such as type 2 diabetes mellitus (T2DM), which impair the quality of life and reduce the longevity of affected individuals, create demands on already-strained health care delivery systems, and generate greater health care costs. Observations gleaned from earlier successes in reducing the rates of smoking and smoking-related diseases can inform efforts to reverse this trend. However, smoking reductions were not accomplished primarily by health care activities. Although interventions in primary care settings played an important role,1 other actions, ranging from media campaigns to policies involving advertising bans, taxation, and smoke-free areas, were critical to changing the dynamics of cigarette use. The behavioral causes of obesity—diet and exercise—are even more strongly rooted in factors outside the health care system. Traditional medical treatments alone cannot substantially lower the prevalence and impact of obesity without changes in the obesogenic environment. Addressing environmental causes recasts diet and exercise as behaviors that are not only a function of individual choice and will power but that are strongly shaped by the resources and obstacles encountered in the environments in which behaviors are enacted.2 The neighborhood effects measured by Christine and colleagues3 documented that individuals residing in neighborhoods marked by limited resources for healthy eating and physical activity (PA) are at higher risk for being diagnosed with T2DM. Based on a rigorous prospective, longitudinal design, their research substantiates the claim that the physical and social contexts of neighborhood environments matter for disease onset.