Understanding Library of Congress Call Numbers

One of the simplest steps in completing a research project is locating library materials on the shelf. Lake-Sumter Community College libraries, like many academic libraries in the U. S., use the Library of Congress Classification System to assign call numbers to most library materials, including books and audiovisual materials. The LSCC Leesburg library also provides a collection of U. S. government documents, which uses the Superintendent of Documents Classification System. This guide will provide an introduction to understanding and using Library of Congress call numbers.

What is the purpose of call numbers?

Each book, videotape, or audiotape has a unique call number, which provides an address or location for the item, and also provides valuable information about it, such as the subject, first letter of the author's last name, and date of publication.

Call numbers appear:

Note that the same call number can be written from top-to-bottom, or left-to-right.

How do you read call numbers?

The Library of Congress Classification System uses a combination of letters and numbers to arrange materials on library shelves by subject:

In what order do call numbers appear on the shelf?

Call numbers are arranged line by line, just as they are read, starting with the letter or letters in alphabetical order:

What information does the call number tell you?

The Library of Congress Classification System arranges materials by subjects. The first sections of the call number represent the subject of the book. The letter-and-decimal section of the call number often represents the author's last name. The last section of a call number is often the date of publication:

Why is this important to know?

Although the most efficient way to locate materials on a particular subject is usually to perform a subject search in the online catalog and then note the call number for each retrieved item, browsing the shelves can also help you locate material appropriate for your topic. Since books are classified by subject, you can often find several helpful books on the same shelf, or nearby. For example, within the subject classification LB 2395, there may be several guides about how to study.

Location Prefixes

Some call numbers begin with a location prefix, which indicates a special collection of materials. For example, materials in the reference collection at each campus library are labelled with an (Ref) prefix. Example: (Ref) LB 2338 .G7 2000.

The LSCC libraries use the following prefixes:

See a librarian to locate these collections in the college libraries.

Source: Text and images on this page were adapted from Honolulu Community College's Understanding Call Numbers.