The National Alzheimer’s Coordinating Center was established by the National Institute on Aging (U01 AG016976) in 1999 to facilitate collaborative research. Using data collected from the 29 NIA-funded Alzheimer’s Disease Centers (ADCs) across the United States, NACC has developed and maintains a large relational database of standardized clinical and neuropathological research data. In partnership with the Alzheimer’s Disease Genetics Consortium (ADGC) and the National Cell Repository for Alzheimer’s Disease (NCRAD), NACC provides a valuable resource for both exploratory and explanatory Alzheimer’s disease research. NACC data are freely available to all researchers.