The Agency for Healthcare Research and Quality (AHRQ) is pleased to release the fourth annual National Healthcare Quality Report (NHQR) on behalf of the U.S. Department of Health and Human Services (HHS) and in collaboration with an HHS-wide Interagency Work Group. Like previous reports, the 2006 NHQR also received significant guidance from AHRQ leadership and AHRQ's National Advisory Committee. The NHQR examines and tracks the quality of health care in the United States, using the most scientifically credible measures and data sources available. Measures of health care quality address the extent to which providers and hospitals deliver evidence-based care for specific services as well as the outcomes of the care provided. The measures are organized around four dimensions of quality-effectiveness, patient safety, timeliness, and patient centeredness-and cover four stages of care-staying healthy, getting better, living with illness or disability, and coping with the end of life. The NHQR is complemented by its companion report, the National Healthcare Disparities Report (NHDR), a comprehensive national overview of disparities in access to and quality of health care among racial, ethnic, and socioeconomic groups, as well as among subpopulations such as children and the elderly. Both reports measure health care quality and track changes over time but with different orientations. The NHQR addresses the current state of health care quality and the opportunities for improvement for all Americans as a whole. This perspective is useful for identifying where the Nation is doing well and where more work is needed. The NHDR addresses the distribution of improvements in health care quality and access across the different populations that make up America. This perspective is useful for ensuring that all Americans benefit from improvements in care. Both reports' perspectives are needed for a complete understanding of quality of healthcare, and both reports support HHS Secretary Mike Leavitt's 500-Day Plan to fulfill the President's vision of a healthier America, specifically in the areas of better transparency of health care quality information and eliminating inequities in health care. The NHQR comprises 211 measures. This large measure set is distilled to 42 core measures which are the major focus of the 2006 report; of these, 40 have data for 2 or more years. The measures are balanced across the four dimensions of quality and provide a more readily understandable summary and explanation of the key results derived from the data. Major additions to the core measures have been made this year. Among them are three new measures on prevention, including advice from health care professionals on eating, exercise, and vision care, and two new composite measures for patient safety, including measures on postoperative complications and adverse events. Also, new measures were added to the overall measure set in the areas of asthma, hospice care, and patient centeredness in hospitals. The Highlights section offers a concise overview of findings from the 2006 NHQR. Four themes emerge from the 2006 NHQR: Most measures of quality are improving, but the pace of change remains modest; Quality improvement varies by setting and phase of care; The rate of improvement accelerated for some measures while a few continued to show Deterioration; Variation in health care quality remains high.