The National Archives and Records Administration (NARA) launched the Archival Research Catalog (ARC) in 2002. ARC was the first centralized system for describing materials held throughout NARA's nationwide system of archival repositories. ARC's complicated development involved the entire agency, as staff wrestled with years of distinct descriptive practices. NARA evaluated external and internal standards, established a consensus-based decision-making structure, and through teamwork, successfully put into practice shared data structure, data content, and data value standards. This article addresses the selection or creation, implementation, and maintenance of the authority files and thesauri that provide data values for ARC access points to ensure consistent and precise retrieval of archival descriptions. (Contains 22 notes.)