Health policy researchers are increasingly turning to insurance claims to provide timely information on cost, utilization, and quality trends in health care markets. This research offers an in-depth description of how to systematically transform raw inpatient and ambulatory claims data into useful information for health care management and research using the Health Care Financing Administration's National Claims History file as an example. The topics covered include: (a) understanding the contents and architecture of claims data, (b) creating analytic files from raw claims, (c) technical innovations for health policy studies, (d) assessing data accuracy, (d) the costs of using claims data, and (e) ensuring confidentiality. In summary, claims data are found to have great potential for quality of care analysis. As in any analysis, careful development of a database is required for scientific research. The methods outlined in this study offer health data novices as well as experienced analysts a series of strategies to maximize the value of claims data for health policy analysis.