Michael S. Wolf, Assistant Professor and Director, Health Literacy and Learning Program, Institute for Healthcare Studies, Feinberg School of Medicine, Northwestern University, Chicago, IL. Terry C. Davis, Professor, Department of Medicine/Pediatrics, Louisiana State University Health Center-Shreveport, Shreveport, LA. Ruth M. Parker, Professor, Division of General Internal Medicine, Emory University School of Medicine, Atlanta, GA. Address correspondence to Dr Wolf, Health Literacy and Learning Program, Institute for Healthcare Studies, Feinberg School of Medicine, Northwestern University, 676 N St Clair Street, Suite 200, Chicago, IL 60611. E-mail: mswolf@northwestern.edu Over the past 2 decades, several hundred studies have depicted associations between limited literacy skills and various problems with health and health care among adults in the United States, lending to the creation of a new field of study that has been aptly named health literacy. Specifically, limited health literacy has been linked to problems with the use of preventive services,1 delayed diagnoses,2 understanding of one’s medical condition,3-5 adherence to medical instructions,6 self-management skills,5-7 physical and mental health,8,9 and increased mortality risk.10 Although less studied, limited literacy has also been associated with higher health care costs.11 But what exactly is health literacy? The definition that has been most widely accepted by academics, policy makers, and clinicians alike is “the capacity to obtain, process, and understand health information and materials needed to make appropriate decisions regarding one’s health.”12 According to the Institute of Medicine’s report, A Prescription to End Confusion, health literacy reflects not only the most fundamental cognitive and social processes associated with learning about one’s health, but it is also the level of complexity attributed to the requisite tasks imparted by the health care system. Despite the dual emphasis in defining the term, the reported prevalence of limited health literacy has usually been derived from estimates of the more general prose, document, and quantitative literacy skills of adult Americans. However, the first national assessment of health literacy skills was recently released.13 The report found more than one third of men and women in the United States to be at the lowest levels of health literacy. More alarming were the disproportionately high rates of low health literacy among racial/ ethnic minorities and low-income adults; more than half of African Americans, adults without insurance coverage, and the elderly had basic or below basic health literacy skills. This reminds us that health literacy is closely aligned with the national concern regarding health disparities.