More than 20 years have passed since the Name Authority Cooperative was conceived. Although not the most senior of cooperative cataloguing initiatives hosted by the Library of Congress, NACO has emerged in terms of size of membership and extent of production as the largest endeavor of its nature in the history of bibliographic control. NACO, which began with an agreement with but a single institution in 1976, now encompasses some 395 institutions that, during the past quarter century, have collectively developed and maintained a database of more than 2,000,000 authority records. The NACO family of libraries is expanding at a rate of about 50 new members annually, while the number of new and updated name and series authority records is currently growing by nearly 220,000 records each year.