Library of Congress Classification System

The Library of Congress Classification System (LC System) is used to organize books in many academic and university libraries throughout the United States and world.

The LC System organizes material in libraries according to twenty-one branches of knowledge. The 21 categories (labeled A-Z except I, O, W, X and Y) are further divided by adding one or two additional letters and a set of numbers.

Understanding LC Call Numbers


A - General Works

B - Philosophy, Psychology, Religion

C - Auxiliary Sciences of History

D - History: General & Outside the Americas

E - History: United States

F - History: United States Local & America

G - Geography, Anthropology, Recreation

H - Social Sciences

J - Political Science

K - Law

L - Education

M - Music

N - Fine Arts

P - Language and Literature

Q - Science

R - Medicine

S - Agriculture

T - Technology

U - Military Science

V - Naval Science

Z - Library Science & Information Resources