The Preassigned Control Number (PCN) Program enables the Library of Congress to assign control numbers in advance of publication to those titles that may be added to the Library's collections.

A Library of Congress control number (LCCN) is a unique identification number that the Library of Congress assigns to the catalog record created for each book in its cataloged collections. Librarians use it to locate a specific Library of Congress catalog record in the national databases.

Only U.S. authors and book publishers are eligible to participate in the PCN Program. For more information on this, please see the Eligibility section of this site.

All forthcoming monographs that will be published in the United States (and that are not included in the categories listed as ineligible in the Scope section of this site) are eligible for the PCN Program.

Library of Congress Control Numbers (LCCN) are preassigned to works that may be selected and cataloged by the Library of Congress for its collections. Final determination of works selected and cataloged is made by selection librarians and recommending officers in compliance with Library of Congress collection development policies upon receipt of the printed book. Please note that while a title may receive a preassigned LCCN, the Library of Congress is under no obligation to provide preliminary or final cataloging information within its catalog for titles that are not ultimately selected for the Library's permanent collection.