The Anesthesia Quality Institute (AQI) was chartered in 2008 by the American Society of Anesthesiologists to develop the National Anesthesia Clinical Outcomes Registry (NACOR). In this Technical Communication, we will describe how data enter NACOR, how they are authenticated, and how they are analyzed and reported. NACOR accepts case-level administrative, clinical, and quality capture data from voluntarily participating anesthesia practices and health care facilities in the United States. All data are transmitted to the AQI in summary electronic files generated by billing, quality capture, and electronic health care record software, typically on a monthly basis. All data elements are mapped to fields in the NACOR schema in accordance with a publicly available data dictionary. Incoming data are loaded into NACOR by AQI technologists and are subject to both manual and automated review to identify systematically missing elements, miscoding, and inadvertent corruption. Data are deidentified in compliance with Health Insurance Portability and Accountability Act regulations. The database server of AQI, which houses the NACOR database, is protected by 2 firewalls within the American Society of Anesthesiologists' network infrastructure; this system has not been breached. The NACOR Participant User File, a deidentified case-level dataset of information from NACOR, is available to researchers at participating institutions. NACOR architecture and the nature of the Participant User File include both strengths and weaknesses.