Library Congress Number Service

Library Congress Number Service


The Library of Congress Control Number (LCCN) is a serially-based system of numbering and cataloging records in the United States Library of Congress.

In its most basic form, the number includes the year of registration and a serial number.  The year has two digits for 1898 to 2000, and four digits beginning in 2001. The three ambiguous years (1998-2000) are distinguished by the size of the serial number.

Librarians all over the world use this unique identifier in the process of cataloging most books which have been published in the United States. It helps them access the correct cataloging data (known as a cataloging record), which the Library of Congress and third parties make available on the Web and through other media.
How It Works


We will complete an application for your LCCN on your behalf and submit it to the Library of Congress.

You will receive your LCCN from us within ten business days.

To be considered for cataloging within the Library of Congress database, we will submit one copy of your book to the Library of Congress.

•An LCCN does not guarantee that your book will be accepted to the Library of Congress catalog; it only offers the opportunity to be considered. The Library of Congress does not provide acceptance or rejection notification. To find out if your book has been cataloged, we suggest occasionally checking the Library of Congress Online Catalog.
•An LCCN can only be assigned to books that have not been previously published. After you have approved your proof, your book is no longer eligible to begin this service.

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