Library of Congress Classification System: Home

Alliant Libraries http://library.alliant.edu

Books in most academic libraries are arranged on the shelves according to the Library of Congress (LC) Classification System. The LC system groups books into 21 broad subject categories which are identified by a letter of the alphabet.The subject categories are further subdivided into double letter or triple letter, detailed subject categories. The specific subject for each book is defined by the number following the first letters.

Example of first part of the call number:

The "B" classification includes books about philosophy, logic, psychology, mythology, aesthetics, and religion. BF is the subdivision for books about psychology. The call numbers in the range BF698-BF698.9 are reserved for books on personality. BF1001-1389 are call numbers reserved for books on parapsychology.

The second part of the call number consists of a single capital letter followed by one digit or more. This usually, but not always, represents the author's name, and is called the "Cutter" number. By putting the Cutter numbers in order within any particular subject call number, the books are arranged alphabetically by author.

A Cutter number may or may not be proceeded by a period on the spine label. Even if the Cutter number is not preceeded by a period you should assume it to be there. The imaginary period is very important in relation to finding materials on the shelves. The period should be treated like a decimal point. These books would be located in this order on the shelf. If the third line of the call number is the same on two or more books use the fourth line to determine the order and location.

The call numbers would be read and shelved as:

BF 175 E3 A8 would come after BF 175 E294 1999 and not before since .294 is smaller than .300.

The final line on the call number is usually the year of publication. The spine label may also include a volume number. Reference books may have "REF" above the call number.

A more detailed outline of the LC Classfication system is located on the Library of Congress website at http://www.loc.gov/catdir/cpso/lcco/

If you have trouble finding a book in the library, please ask for assistance.

Updated 5/5/2015 by rschiff

Reviewed: 5/9/2013 RES