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Call Numbers: LC and DD Classification Systems: Library Classification Systems

Introduction to Library of Congress and Dewey Decimal classification systems

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This guide will introduce you to two main classification systems that most libraries in the US use to organize their library collection. They are called Library of Congress classification system, and Dewey Decimal classification system.

The Library of Congress Classification System (LCCS) was developed in the late 19th and early 20th century to organize the book collections of the Library of Congress (LC). Over time, the LC system has been adopted by many libraries, especially big Academic Libraries around the world. The LCCS divides all knowledge into 21 basic classes identified by a single letter of the alphabets.

The Dewey Decimal Classification (DDC) system was developed by Melvil Dewey in 1876. The DDC divided all knowledge into 10 basic classes identified by numbers. Below is a list that maps the LC headings to DDC.

Mapping of Library of Congress Classification System (LCCS) headings to Dewey Decimal Classification (DDC) system

                LCCS                      DDC
A General Works 000 Generalities
B Philosophy, Psychology, Religion  100 and
Philosophy, Religion &   Psychology
C History of Ancient World, History
of Civilization
930 and
History of Ancient World (to circa 499 AD), General History 
D World History and History of Europe, Asia, Africa, Australia, New Zealand  909  World History 
E History of the Americas  970-979  History of North America 
F History of the Americas 980-989  History of South America 
G Geography, Anthropology, Recreation 900 Geography and History
H Social Sciences 300 Social Sciences 
J Political Science 379  Government Regulation, Control, Support 
K Law  340-349  Law 
L Education 370-378  Education
M Music and Books on Music  780-788  Music
N Fine Arts  700 The Arts
P Language and Literature  400 and 800 Language and Literature & Rhetoric
Q Science 500 Natural Sciences & Mathematics 
Medicine  610-619 Technology (Applied Sciences) 
S Agriculture  630-639  Agriculture 
T Technology 620-629 Engineering 
U Military Science 355  Military Science 
V Naval Science 359  Sea (Naval) Forces and Warfare 
Z Bibliography, Library Science, Information Resources (General) 020-028 

Library & Information Sciences 

Sources: "Library of Congress Classification Outline". The Library of Congress. n.d. Web. 3 Jul. 2012. (

Sources: "Library of Congress Classification Outline". The Library of Congress. n.d. Web. 3 Jul. 2012. (
"Dewey Decimal System: A Guide to Call Numbers". University Library, University of Illinois at Urbana Champaign. 6 Jun. 2011. Web. 3 Jul. 2012. (