Examining health care disparities is an integral part of improving health care quality. Health care disparities are the differences or gaps in care experienced by one population compared with another population. As the National Healthcare Quality Report (NHQR) shows, Americans too often do not receive care that they need or they receive care that causes harm. The National Healthcare Disparities Report (NHDR) shows that moreover, some Americans receive even worse care than other Americans. The quality of health care is different for different people. Within the scope of health care delivery, these disparities are due to differences in access to care, provider biases, poor provider-patient communication, poor health literacy, and other factors. The purpose of the NHDR, as mandated by Congress, is to identify the differences or gaps where some populations receive poor or worse care than others and to track how these gaps are changing over time. Although the emphasis is on disparities related to race, ethnicity, and socioeconomic status, this directive also includes a charge to examine disparities in "priority populations." These include groups with unique health care needs or issues that require special attention. Among the priority populations addressed in the NHDR are women, children, older adults, residents of rural areas, and individuals with disabilities or special health care needs. The NHDR uses the same 220 measures used in the NHQR categorized across four dimensions of quality: effectiveness, patient safety, timeliness, and patient centeredness. This year's report focuses on the state of health care disparities for a group of 45 core measures that represent the most important and scientifically credible measures of health care quality for the Nation, as selected by the Department of Health and Human Services (HHS) Interagency Work Group. By focusing on core measures, the 2008 report provides a more readily understandable summary and explanation of the key results derived from the data. While the measures selected for inclusion in the NHDR are derived from the most current scientific knowledge, this knowledge base is not evenly distributed across the dimensions of health care quality, nor across racial, ethnic, and other priority populations. The analysis in the following pages centers on measures for which data are available and that fit within the framework provided by the Institute of Medicine. Three key themes emerge in the 2008 NHDR: Disparities persist in health care quality and access; Magnitude and pattern of disparities are different within subpopulations; Some disparities exist across multiple priority populations.