Dewey Decimal System Day is observed on December 10, the birthday of Melvil Dewey, who created the library classification system that bears his name. If you've ever found a book on a library shelf using a call number like 599.75 for big cats, you've used the Dewey Decimal System. The day celebrates libraries, librarians and the clever system that helps millions of people find information every day.
History of Dewey Decimal System Day
Melvil Dewey was born on December 10, 1851, in Adams Center, New York. While working as a student assistant in the library at Amherst College, he developed a way to organize books by subject using numbers and decimals. He published the system in 1876.
The Dewey Decimal Classification divides knowledge into ten main classes, from 000 for general works and computer science to 900 for history and geography. Decimals allow subjects to be divided into finer and finer topics. Unlike earlier systems that assigned books to fixed shelf locations, Dewey's system organized books by subject, so new books could be added in the right place.
In 1876, Dewey also helped found the American Library Association. His legacy is complicated: he was a major library innovator, but he was also accused of discriminatory and inappropriate behavior, and in 2019 the ALA removed his name from one of its top awards. Today, the system is maintained by the library cooperative OCLC and is used in libraries in more than 135 countries, especially public and school libraries.
Why Dewey Decimal System Day Matters
The Dewey Decimal System makes libraries easier to use, grouping related books together so readers can browse and discover.
Learning how call numbers work is a useful information literacy skill for students and lifelong learners.
The day also celebrates libraries and librarians, who help people find reliable information, and invites a thoughtful look at how history remembers complicated figures.
How to Celebrate Dewey Decimal System Day
- Visit your library: browse a section by Dewey number.
- Learn the ten classes: memorize the main categories.
- Find a book by call number: practice using the catalog.
- Thank a librarian: recognize the people who organize knowledge.
- Organize your shelf: sort your home books by subject.
Celebrating at Work, School and Home
At work, organize the office bookshelf or shared drive by topic, inspired by Dewey's system. In classrooms, students can play library scavenger hunts using call numbers, sort books into the ten classes, or create a classification system for their own collections. At home, families can visit the library together, get library cards, and practice finding books with call numbers. Kids enjoy learning that dinosaurs are in the 560s and pets in the 636s.
Fun Facts About Dewey Decimal System Day
- Melvil Dewey published his system in 1876.
- The system has ten main classes, from 000 to 900.
- Dewey helped found the American Library Association in 1876.
Dewey Decimal System Day FAQs
When is Dewey Decimal System Day?
Dewey Decimal System Day is observed on December 10, Melvil Dewey's birthday.
What is the Dewey Decimal System?
It is a library classification system that organizes books by subject using numbers from 000 to 999.
When was the Dewey Decimal System created?
Melvil Dewey published it in 1876.
What are the ten Dewey classes?
General works, philosophy and psychology, religion, social sciences, language, science, technology, arts, literature, and history and geography.
Do all libraries use the Dewey Decimal System?
No. Many academic libraries use the Library of Congress Classification instead.
Why was Dewey's name removed from an ALA award?
In 2019 the ALA cited his history of discriminatory and inappropriate behavior.