The Bethesda System for gynecologic cytopathology has standardized reporting terminology over the past quarter of a century. In doing so, it has allowed for improved communication among practitioners around the world, facilitated large research projects and clinical trials, and has provided the basis from which uniformly accepted risk-based management strategies have been developed. Over time, changes in terminology and the underlying science require revisions, and the third edition of the Bethesda "Atlas" is the result of a yearlong effort to provide such an update. New material was developed and proposed via an Internet bulletin board, allowing for wide commentary that was compiled and incorporated. New images were collected, which comprised many new examples of equivocal presentations and mimics. New background material on the scientific basis supporting the terminology categories, the most current management algorithms, and comprehensive references were included. The effort completely refurbishes this standard reference that forms an inexpensive and, therefore, widely available resource for the world's cytology community.