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Finding materials on the shelves: LC Classification system

Library of Congress classification

The ECAE Library uses the Library of Congress (LC) classification system. This system organizes books and other library materials by subject, to make it easier for you to browse the shelves for materials on a specific topic. Library of Congress call numbers always begin with letters of the alphabet. This system is organized into 21 main classes which are designated by letters of the alphabet.

It is possible to search by call number in the library catalog. The partial outline below may also be useful for browsing the shelves:

  • A -- General Works
  • B -- Philosophy, Psychology, Religion
  • C -- Auxiliary Sciences of History (Genealogy, Archaeology, Biography, etc.)
  • D -- History (General) and History of Europe
  • E -- History: America
  • F -- History: America
  • G -- Geography, Anthropology, Recreation
  • H -- Social Sciences
  • J -- Political Science
  • K -- Law
  • L -- Education
  • M -- Music and Books on Music
  • N -- Fine Arts
  • P -- Language and Literature
  • Q -- Science
  • R -- Medicine
  • S -- Agriculture
  • T -- Technology
  • U -- Military Science
  • V -- Naval Science
  • Z -- Bibliography, Library Science

Each book is given a unique call number according to the LC system, and the books are arranged on the shelves in order by that call number which is alphanumeric.

The following call numbers are in order as you would find them on the shelf. Note that the first number in the call number is treated as a whole number (PS25 comes before PS132) and that the second number is treated as a decimal (G294 comes before G38).

 Call Number Examples in Order

PA

2143

.R24

PS

25

.F12   

PS

132

.G294

PS

132

.G38

PS

1163

.B26

See the Library of Congress Classification Outline for the complete classification system.

Reading a Call Number

  • LC call numbers are first arranged alphabetically, according to the letter or letters at the beginning of the call number, which correspond to the subject matter of the item. 
    Example: Call numbers beginning with P are followed by PA, PB, PC, etc.
  • Within the alphabetical section, books are arranged by the number(s) that follow. Notice that these numbers are regarded as whole numbers. For instance, PS 1200 comes after PS 345. 
    Example: QA 56 before QA 234 before QA 234.57 before QA 234.8
  • The next lines are alphabetic, then numeric as a decimal. The numerical part of this section is a decimal number, not a whole number. Use alphabetical order first, then the decimal extension to put the call numbers in correct sequence. (A3113 would come before A4, because 0.3113 is smaller than 0.4.) 
    Example: HV 1431 .B7 before HV 1431 .B83 before HV 1431 .F25 before HV 1431 .F7
  • Editions are often arranged by date or by the date and letters. 
    Example: PS 3525 .I52 1971 before PS 3525 .I52 1973 before PS 3525 .I52 1973a

Call number

You can think of a call number as a book's address on the shelf.

The majority of books that you will come across in the Libraries will have a Library of Congress Call Number. Call number labels are located on the lower part of the spine of the book. Reference materials, in addition, will be marked REF on the call number label.

The first line in a Library of Congress call number classifies the item by its subject according to the LC Classification System. The entire call number should be noted in order to locate the item.

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LC Classification system in Academic libraries

How to read call numbers in an academic library

Libraries use classification systems to organize the books on the shelves. A classification system uses letters and/or numbers (call numbers) to arrange the books so that books on the same topic are together. This arrangement results in "serendipitous browsing:" you find one book in the catalog, go to the shelf, and, an even better book is sitting right next to it.

From the Online Catalog to the Shelf

Libraries in the United States generally use either the Library of Congress Classification System (LC) or the Dewey Decimal Classification System to organize their books. Most academic libraries use LC, and most public libraries and K-12 school libraries use Dewey.

Call number 'LB 2395 .C63 1991' on the spine of a book and in the online catalog

Anatomy of a Library of Congress Call Number

Call number 'LB 2395 .C65 1991' on the spine of a book and in the online catalog

Book title: Uncensored War: The Media and Vietnam
Author: Daniel C. Hallin
Call Number: DS559.46 .H35 1986

The first two lines describe the subject of the book.
DS559.45 = Vietnamese Conflict

The third line often represents the author's last name.
H = Hallin

The last line represents the date of publication.

Tips for Finding Books on the Shelf

Call number 'LB 2395 .C65 1991' on the spine of a book and in the online catalog

Read call numbers line by line.

LB
Read the first line in alphabetical order:
A, B, BF, C, D... L, LA, LB, LC, M, ML...

2395
Read the second line as a whole number:
1, 2, 3, 45, 100, 101, 1000, 2000, 2430...

.C65
The third line is a combination of a letter and numbers. Read the letter alphabetically. Read the number as a decimal, eg:
.C65 = .65 .C724 = .724

Some call numbers have more than one combination letter-number line.

1991
The last line is the year the book was published. Read in chronological order:
1985, 1991, 1992...

Here is a shelf of books with the call number order explained.

Ten Library of Congress call numbers in order on a shelf. On the first line, 'LA' before 'LB'. On the second line, '2327' before '2328'. On the combination letter number line 'B' before 'C'. For the numbers after the letter on the combination line, '.55' before '.554' and '.554' before '.63'. For the last line, '1987' before '1991'.

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