Comparison of Dewey and Library of Congress subject classification

The Dewey Decimal Classification (DDC) was first published by Melvil Dewey in 1876,^[3][4] and included a detailed justification for his use of decimal notation.^[5] DDC decimal notation ID can be expanded or reduced as needed by libraries.^[3] It was designed for medium and small sized collections,^[6][7] including those found in public libraries, school libraries, and small academic libraries.^[8][9][10] It consists of ten numeric classes that represent broad fields of study.^[9][8][11] Using numbers, each class is divided into ten divisions or subclasses.^[1][11] During the cataloging process, each item is assigned a three-digit DDC number that represents class, division, and section, followed by a cutter number that identifies the author.^[12] For example, the call number 813.54 M37 includes 800 for the main class of literature, 810 for the division of American literature in English, 813 for American fiction in English, and the cutter M37 for the author.^[12]

The Library of Congress Classification (LCC) was introduced in 1900, based on the collection of the Library of Congress, the largest library in the world.^[3][13] LCC was adopted by other institutions with larger or specialized collections, such as those found in academic libraries and research libraries.^{[14][3][8][10]} In 2019, 81 percent of US academic libraries and 93 percent of Nigeria's academic libraries used the Library of Congress Cataloging system.^[15] LCC has 21 main classes, each designated with a letter of the alphabet, excluding I, O, W, X, and Y which are used to accommodate special needs of libraries that use the classification scheme.^[2][9][16] Its alpha-numeric call numbers include four parts: class/subclass, topic, cutter number, and publication date.^[8][1] For example, HV4708 .R83 2011, where HV stands for social sciences, 4708 is the topic social welfare, .R83 is the cutter number which represents the author, and 2011 is the year of publication.^[8]

Both classification systems are used to create a functional topical order of the resources on the library shelves.^[4] They vary in their notation: DDC is a numeric classification system, while LCC is an alpha-numeric system.^[17][13] LCC was developed specifically for the Library of Congress collection, while DDC was created as a system that could be adapted to a variety of library sizes and specialties.^[13] D. Kent Halsted noted, "Neither scheme is perfect nor will ever be."^[4] As with any classification system, both DDC and LCC include the bias of their creators; in this case, both systems were developed by white, Christian, male academic scholars in late 19th century America.^[18]

There are various factors that determine which classification system a library uses.^[4] The global library cooperative OCLC notes that "A library should base its decision on close versus broad classification on the size of its collection and the needs of its users."^[19] Usually, the size of a library's collection determines whether it selects DDC or LCC.^[9] While DDC was designed for medium-sized libraries,^[6] LCC allows libraries with larger collections to be more specific or precise with classifications.^[9][8][4] Thus, DDC is preferred by institutions with collections under 200,000, while LCC is recommended if the collection includes more than 500,000 items.^[4][20] In the 1960s and early 1970s, many larger academic libraries changed from Dewey Decimal Classification to Library of Congress Classification.^[21][4] After converting the college's library from DCC to LCC in 2021, West Coast Baptist College's director of library services Alyssa Sultanik concluded,

LCC tends to divide resources into smaller subclasses and may be more suitable for larger collections. Several factors can play a part in the success of LCC, such as the practicality of LCC for academic libraries, the ease of use in a specialized collection, and the ability to grow for expanding libraries and the ability to easily add new topics as needed. The collection size, depth of the materials, and intended use of the library collection should be considered when choosing between classification systems...Smaller collections may be more suited for DDC because of the classification's more generalized nature.^[16]

The following table compares the organization of resources by the Dewey Decimal and Library of Congress classification systems.^{[11][22][23][24][25][26][27]} It includes all 99 second-level (two-digit) Dewey Decimal classes (excluding 040), and all second-level (two-digit) Library of Congress classes.

• Classification
• Decimal classification
• Library catalog
• Library of Congress Subject Headings
• List of Dewey Decimal classes

• Billy, Amber; Nelson, Elizabeth; and Uhl, Rebecca. Inclusive Cataloging: Histories, Context, and Reparative Approaches. Chicago: ALA Editions, 2024. ISBN 979-8-89255-566-1.
• Chan, Lois Mai. A Guide to the Library of Congress Classification, 6th ed. New York: Libraries Unlimited, 2016. ISBN 978-1440844331.
• Chan, Lois Mai and Salaba, Athena. Cataloging and Classification: An Introduction. Lanham, Maryland: Rowman & Littlefield Publishers, Inc., 2016. ISBN 9781442232495.
• Merkley, Carl. "The Library of Congress, Dewey Decimal, and Universal Decimal Classification Systems are Incomplete and Unsystematic". Evidence Based Library and Information Practice, vol. 6, no. 4 (2011): 134–136. doi.org/10.18438/B8QK7S.
• Satija, M. P. The Theory and Practice of the Dewey Decimal Classification System. Hull: Chandos Publishing, 2013. ISBN 978-1843347385.
• Scott, Mona L. Dewey Decimal Classification: A Study Manual and Number Building Guide, 22nd edition. New York: Libraries Unlimited, 2005. ISBN 978-1591582106.
• Sroka, Marek. "Library of Congress Subject Headings, Dewey Decimal Classification and the Ambiguity of Subject Representation of Central, Eastern and South-Eastern Europe in American Knowledge Organization Systems." Central European and Balkan Studies, vol. 33 (November 21, 2024): 9–16. doi.org/10.4467/2543733XssB.24.001.20025
• Weihs, Jean and Intner, Sheila S. Beginning Cataloging, 2nd edition. Bloomsbury Publishing, 2016. ISBN 9798216052197.