It has long been recognized that repeated impacts to the head, as occurs in professional boxing, results in a neurodegenerative disease that was initially called dementia pugilistica and is now referred by the more descriptive term of chronic traumatic encephalopathy (CTE).1 This recognition, which led the American Medical Association to call for a ban on the sport,2 was paralleled by a decline in the sport's popularity, at least among the mainstream culture in the United States. More recently, the growing awareness that CTE also occurs in retired professional football players has received widespread attention in the national media and in the scientific literature.3 Of particular concern is the possibility that serious neurologic sequelae of repeated mild traumatic brain injuries (MTBIs) are not limited to professional football players but may also occur in amateur collegiate athletes and even adolescent and younger players. Initiatives such as the recent donation by the National Football League (NFL) of $30 million to the Foundation for the National Institutes of Health hold out the promise that critical research in the relationship between MTBIs (also commonly referred to as concussions) and neurodegenerative disorders will be forthcoming in the near future. Beyond the pathologic recognition that CTE occurs in some NFL veterans, careful prospective epidemiologic studies are needed to answer critical questions, such as the following: what is the true incidence of CTE, what factors are associated with increased risk for neurodegeneration, and, most importantly, what can be done to ameliorate risk or prevent neurologic disability? Because the symptoms of CTE, such as irritability, depression, and cognitive problems, are protean and nonspecific, biomarkers and neuroimaging to complement the clinical examination will likely be essential and will improve the accuracy of the diagnosis during the lifetime of the individual and will be used to follow the natural history of the illness. It is in this light that the report by Hart et al4 in this issue of the journal merits attention.