Understanding Call Numbers

Dewey Decimal Call Numbers

The Dewey Decimal Classification System is subject based, classifying and arranging items by the subject matter involved. LSU Libraries uses Dewey call numbers for materials in the Educational Resources Center, for theses and dissertations, and for older items which are used infrequently and are kept in compact storage.

  • Dewey call numbers begin with a three digit number

  • The Dewey system is broken into 10 primary classes, or general subject areas, represented by the first digit of that number
    • 000 - Generalities
    • 100 - Philosophy & Psychology
    • 200 - Religion
    • 300 - Social sciences
    • 400 - Language
    • 500 - Natural sciences & Mathematics
    • 600 - Technology
    • 700 - The arts
    • 800 - Literature & Rhetoric
    • 900 - Geography & History

  • The Dewey system further breaks these subjects into subclasses by the addition of the next two digits, and then often even adding a decimal point and more numerical digits. For example:
    • 500 Dewey call numbers deal with Natural Sciences & Mathematics
    • 590 Dewey call numbers deal with Zoological Sciences
    • 599 Dewey call numbers deal with Animals
    • 599.884 Dewey call numbers deal with Gorilla Behavior

  • For a list of the major classes and subclasses of the Dewey Decimal classification system, click HERE.

  • The second part of a Dewey call number is based on the Author's last name.
    • Some libraries use only the author's name, or the first letters of the author's name.
      For example, the call number for Gorillas in the Mist, by Dian Fossey would be:
      599.884 FOS
    • Some libraries use the first letter, or letters of the author's name followed by numbers representing the author and the particular item.
      In this case, the call number for Gorillas in the Mist is:
      599.884 F752g

  • Frequently a Dewey call number will include a third part which represents the year that the item, or particular issue of an item, is published.
    Again, the call number for Gorillas in the Mist:
    599.884 F752g 1983


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