Sarah Thomas came to Cornell in 1996 from the Library of Congress, where she held positions overseeing the library's public services, special collections and cataloging directorate. She was the Karl A. Kroch Cornell University Librarian and Under Thomas' leadership, the library continued to build its rare and special collections and embraced the digital age, developing a suite of online services and offering 24-hour worldwide access to a rich array of online journals and other electronic media. Thomas was the principal force behind Project Euclid, a Mellon Foundation-funded initiative to support the cost-effective online dissemination of mathematics and statistics journals. While at Cornell she served on the executive board of the Association of Research Libraries for six years and was its president in 2004-05. She also chaired the Digital Library Federation Steering Committee and was a member of the board of the Research Libraries Group.