Researchers have long been interested in the relationship between literacy and health. Over the past several decades, many studies have been conducted to analyze the difficulty of health-related print materials, evaluate patients' ability to read these types of materials and to recognize common medical terms, and determine whether patients' literacy skills have an effect on health outcomes, such as self-care and disease management. This report seeks to further illuminate the relationship between literacy and health using data from large-scale surveys of adult literacy--the National Adult Literacy Survey (NALS) and the International Adult Literacy Survey (IALS)--conducted by Educational Testing Service for the U.S. Department of Education. Included in these assessments were a variety of health-related materials on topics such as drugs and alcohol, disease prevention and treatment, safety and accident prevention, first aid, emergencies, and staying healthy. Survey respondents were asked to perform different literacy tasks based on these materials--for example, to read a medicine dosage chart and indicate the correct dose for a child of a particular weight and age, or to interpret information from a news article on bicycle safety. The survey also gathered extensive background information about respondents' demographic and socioeconomic characteristics, as well as their health status, literacy practices, and civic participation. For the current study, researchers analyzed performance results for the 191 health-related tasks included in the large-scale literacy assessments. In doing so, they were able to create a new Health Activities Literacy Scale (HALS) linked to the NALS database. The HALS is a 0 to 500 scale that reflects a progression of health-related literacy skills from low (Level 1) to high (Level 5). Using the new HALS scale, the authors estimate the distribution of literacy on health-related tasks among U.S. adults, describe the health literacy skills of at-risk or vulnerable population groups, and demonstrate how health-related literacy is connected to health status, wealth, and civic engagement. Appended are: (1) Methodological Approach to Creating the HALS; and (2) Comparison of Mean Scores on the HALS and the NALS by Selected Background Characteristics. (Contains 18 tables, 10 figures, and 57 footnotes.)