According to a report on chronic diseases by Centers for Disease Control and Prevention researchers, published in The Lancet as part of a new Series, The health of Americans , half of all adults in the USA suffer from at least one chronic condition, such as diabetes, heart disease, or obesity, and over a quarter of adults have two or more. The majority of these chronic conditions stem from a small number of risk factors that are largely preventable, including tobacco use, poor diet, and physical inactivity (both strongly associated with obesity), alcohol consumption, and uncontrolled high blood pressure. The report indicates Medicare enrollees (the majority of whom are over 65) accounted for US$300 billion in health care spending, over 90% of which was accounted for by people with two or more chronic conditions. Compared with comparable high-income countries, the USA is less healthy in areas such as obesity, heart disease, diabetes, and chronic lung diseases. Reduction of the chronic disease burden in the USA will require coordinated action, including epidemiology and surveillance to monitor trends and track progress, policies and environments that promote health and support healthy behaviours, healthcare that effectively delivers prevention services, and stronger links between health care and community services.