Skip to Main Content

Library of Congress Classification Conversion Project

Library of Congress Classification

What is classification and why do we need it?
In general, classification is a system for categorizing and organizing information. The purpose of classification in libraries is to provide a location to find a specific item and to bring related items together in a useful sequence. Library classification systems are selected based on the content of a library’s collection.

What is Library of Congress Classification?
Library of Congress Classification (LCC) was developed by the United States Congressional Library for organizing its own collection but is used worldwide as a standard for academic and research institutions. LCC divides "all knowledge" into twenty-one basic classes, each identified by a single letter of the alphabet, that are roughly equal to academic disciplines or areas of study.


Dewey Decimal Classification (DDC)

  • 000: Generalities
  • 100: Philosophy & Psychology
  • 200: Religion
  • 300: Social Sciences
  • 400: Language
  • 500: Natural Sciences & Mathematics
  • 600: Technology (Applied Sciences)
  • 700: The Arts
  • 800: Literature & Rhetoric
  • 900: Geography & History

Library of Congress Classification (LCC)

  • A: General Works
  • B: Philosophy, Psychology, Religion
  • C-F: History
  • G: Geography, Anthropology
  • H-L: Social Sciences
  • M: Music
  • N: Fine Arts
  • P: Language & Literature
  • Q-T: Science & Technology
  • U-V: Military and Naval Science
  • Z: Bibliography, Library Science, Information Resources


How to Read a LC Call Number

Libraries have specialized tools and training on how to create call numbers but understanding the basics will help you find what you are looking for quickly and make browsing easy.

LCC uses letters and numbers to describe what a book is about, who wrote or edited it, and when it was published. For example, let’s look at a call number for The Grapes of Wrath by John Steinbeck:

PS 3537 .T3234 G8 2018

On the spine label, the call number is arranged vertically by part:

The LCC system uses the beginning letters and first line of numbers to indicate the subject of the book. In this example, the alphanumeric lines tell us that this book is on the shelf with other American literature books.

The next two lines are Cutters, which use a combination of characters to further specify a book's identity and shelf location. In this example, the first line represents the author, John Steinbeck. Other books written by or about John Steinbeck will have the same Cutter so they will be grouped together on the shelf. The second Cutter represents the title of this book.

The last line is the date of publication. It is a visible way to indicate the edition of the book and helps us to shelve the book in chronological order. In this example, we know that this book was published in 2018.