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Dewey® Services

Provide future librarians with the knowledge they need

If you teach others about the Dewey Decimal Classification® (DDC) system, you need reliable resources to help plan and produce an effective curriculum. While we are building additional resources for you, we hope you'll find this brief history and introduction to the DDC helpful.

Dewey training courses

We have developed an online set of training materials for the DDC focused on the needs of experienced librarians who need Dewey application training. We hope the materials will also be useful as supplementary materials in other Dewey training contexts, such as teaching Dewey to students in Library and Information Science programs. The materials include modules on general principles governing the operation of the DDC as well as modules on the structure and use of specific tables and main classes.

All course materials are available at no charge. The presentations and exercises assume the availability of the latest version of the DDC database (WebDewey) and a professor, trainer and/or experienced Dewey user for offering explanations and fielding questions. Other interested parties may have access to course materials but may need to consult an expert directly for background information and additional assistance. Note that WebDewey access is provided without cost as part of OCLC's Library and Information Science Education Program. Others currently without access to WebDewey can sign up for access on a 30-day trial basis.

The following table contains links to the descriptions of each module on the Dewey blog. We welcome comments directly on the blog entry for each module. If you prefer to send comments privately, please send them to dewey@loc.gov with the subject line of the module, and we will summarize them on the Dewey blog.


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

  • Dewey Services

    Available everywhere

Learn more

brochure coverDownload 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.

Past and recorded events

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Recent news

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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.