What is an Library of Congress Number?

(click here to download form)

A Library of Congress catalog card number is a unique identification number that the Library of Congress assigns to the catalog record created for each book in its cataloged collections. It is a control number librarians use it to locate a specific Library of Congress catalog record in national databases and to order catalog cards from the Library of Congress or from commercial suppliers. The Library of Congress assigns this number while the book is being cataloged. Under certain circumstances, however, a card number can be assigned before the book is published through the Preassigned Card Number (PCN) program.

Publishers may request that a Library of Congress catalog card number be preassigned to a forthcoming title by submitting a one-page application form. The title must meet the eligibility requirements specified in this brochure and, as noted, the application must be submitted prior to publication. A number cannot be preassigned to a book that has already been published.

Requests are processed within five working days after receipt of the application form. The form is returned to the publisher, bearing the card number in the box provided. The publisher then prints the preassigned number on the back of the title page (copyright page) preceded by the phrase, “Library of Congress Catalog Card Number.” If the title is not eligible, the publisher is notified promptly that no card number can be preassigned.

There are no fees for participation in the program. However, the publisher must send a non-returnable complimentary copy of the best edition (e.g., the hardcover edition if published in both hardcover and paperback) of the work to the CIP Division upon publication. This copy is to be supplied in addition to any copies which are deposited with the Copyright Office.

What types of books are eligible for a LCC number?

All forthcoming monographs that will be published in the United States and that do not fall into one of the categories listed below are eligible for the PCN program. Card numbers are preassigned to materials which are most likely to be selected and cataloged by the Library of Congress for its own collections.