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As libraries increased in size and complexity during the later part of the nineteenth century, librarians were faced with the challenge of organizing materials in a systematic manner. Several classification schemes were developed as a result, but the most successful was Melvil Dewey's Decimal Classification scheme. Dewey originally devised the system in 1873 while serving as the librarian at Amherst College, but it wasn't until 1876 that the first edition of the Decimal Classification was published.

Dewey's scheme works on the principle that all knowledge can be organized into 10 broad catagories, with hierarchies based on ten allowing for greater specificity. The 22nd Edition (2003) of the DDC lists the 10 main classes as:

As works become more specific, the call number adds another hierarchy and becomes longer. For example, a general work on United States history would have a short number:

While a work on propaganda during the Revolutionary War would have a longer classification number:

The arrangement of the system allowed for works on the same subject to be clustered together, allowing for greater ease with browsing. Since the system can be continually divided into smaller and smaller hierarchies, it is theorically infinite and can be expanded as new knowledge and disciplines appear.

No classification system is perfect, and there are some major faults with the DDC. Confusion over where cross-discipline works should be classified are common, with the possibility of a single work having multiple correct classification numbers. Of greater concern today is the Anglo-centric nature of Dewey's hierarchy. An example of this is found in the 400 hierarchy. The entire 430 hierarchy is given to Germanic languages, but all works in Chinese must be squeezed under 495.1 heading. As a result of this, the DDC can be very difficult to use for non-Western materials.

In spite of its faults, the Dewey Decimial Classification has become the most widely used classification scheme in libraries worldwide, and has been the basis for other systems, notably the Universal Decimal Classification system (UDC), most often used in Europe. In the US, the DDC is commonly used in public and small libraries. It is continually under revision by OCLC and the Library of Congress, allowing for the inclusion of new topics and changing methods of organizing information. Librarians at these organizations usually assign about 110,000 DDC numbers to works published in a given year. To keep up with these changes, OCLC periodically updates the DDC. The most current revision is the 22nd edition, completed in 2003.

Sources:

Linderman, Winifred B. "Dewey, Melvil." Encyclopedia of Library and Information Science. 2nd ed. Ed. Miriam A. Drake. New York: Marcel Dekker, Inc. 2003. p. 839-849.

Miksa, Francis L. "Classification." Encyclopeida of Library History. Ed. Wayne A. Wiegand and Donald G. Davis, Jr. New York: Garland Publishing, 1994. 144-153.

Mitchell, Joan S. et al., ed. Dewey Decimal Classification and Relative Index 22 ed. Dublin, OH: OCLC Online Computer Library Center, Inc. 2003.

By Katie H.

Back to 1870s