Organize your materials with the world's most widely used library classification system.

Organize your collection
Libraries big and small the world over use the Dewey Decimal Classification® (DDC®) system to help make sense of today's complex library collections.
Break down language barriers
The DDC system has been translated into more than 30 languages and serves library users in more than 200,000 libraries in 135+ countries worldwide, making it the world's most widely used library classification system. More than 60 of these countries use the DDC to organize their national bibliographies.


Get timely updates
Integrate updates to the DDC through continual updates to the WebDewey® service.
Minimize volunteer and staff training time
Many libraries rely on volunteers and temporary staff to manage day-to-day tasks such as re-shelving books. The DDC's simple, number-based format makes it easy for these helpers to know exactly where a book should fit on the shelf. They can re-shelve books quickly and have confidence they're doing it correctly.


Help patrons feel more comfortable in the library
Non-regular library users can be intimidated by the rows and rows of shelves, searching the catalog, and even asking a librarian for help. With its subject-based classification system, the DDC encourages patrons to independently browse the catalog, the stacks, and even your programming schedule to find what they need. Once they find the topic area they want, patrons can comfortably browse the items to get a better understanding of your collection.
"Delaware Libraries use the Dewey Decimal Classification system as a match point across all library services—including reference, programs, and circulation—to get a sense of how Delawareans are using libraries and what they are trying to accomplish."
Annie Norman
State Librarian/Director
Delaware Division of Libraries
Delaware, United States
The Dewey Decimal Classification® (DDC®) system is the world’s most widely used way to organize library collections. The DDC constantly updates to enable better discovery across any topic in multiple languages. Because the DDC is easy to use, you can increase the visibility of your materials quickly and efficiently.
Service availability
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Dewey Services
Available everywhere
Learn more
Download the Dewey Services brochure
Download the brochure (US Letter)
Download the brochure (A4)
The Dewey blog is a great source for news and views on classification issues as well as interesting and unusual DDC resources and curiosities. It's also a convenient way to share feedback directly to the DDC editors to help shape the future of the DDC.
Upcoming events
21 June 2018
American Library Association's Annual Conference
Past and recorded events
20 March 2018
Public Library Association Conference
All copyright rights in the Dewey Decimal Classification system are owned by OCLC. Dewey, Dewey Decimal Classification, DDC, OCLC and WebDewey are registered trademarks of OCLC.