The Yale University Library catalog (ORBIS) contains nearly 7 million bibliographic records and over 2 million authority records. These authority records help staff maintain consistent headings in the catalog. They also generate cross references that facilitate searching. The Library creates its new authority records in OCLC as a member of the cooperative cataloging program called NACO. These records become part of the master authority file of the Library of Congress and are shared with libraries throughout the world. The Library also relies on the MARS service to help maintain authority control in ORBIS. This service corrects headings in new bibliographic records, supplies new and changed authority records, and provides reports that facilitate retrospective database cleanup activities.