The Dewey Decimal System: What it is and How to use it. A How-To Guide from O’Fallon Public Library

The Dewey Decimal Classification system is the most common way non-fiction library collections are organized. That being said — who invented it, what is it and how do you use it?

Who was Mevil Dewey? A brief history.

Melville Louis Kossuth Dewey was born in December 1851. From an early age, he showed an interest in simplifying concepts. For example, he dropped his middle names, shortened his first name to Melvil and spelled his last name as Dui. (The Dui spelling didn’t last; the first name shortening did.)

Melvil Dewey

Dewey invented the system that would go on to such worldwide popularity when he was 21. While he created it, he worked in the library of Amherst College. He used some of the qualities of existing systems like Sir Francis Bacon’s classification of knowledge, and systems by William Torrey Harris and Natale Battezzati in order to create his own unique system.

In addition to developing the Dewey Decimal System, Dewey participated in the 1876 establishment of the American Library Association and helped create the Library Journal. Dewey went on to be Columbia University’s librarian. And, in 1887, he founded the first library school in the world.

Melvil Dewey died on 26 December, 1931. He was 80 years old.


The Dewey Decimal System

So, what is the system that has been used by more than 200,000 libraries in 135 countries?

It is a numbers system that is divided by topic.

Photo by Valeria Ushakova on Pexels.com

For example, let’s say you’re looking for a book about gardening. Gardening can be broken down into specific topics like garden design, the history of gardening, organic gardening. These topics are located near each other in the numbered system.

The history of gardening is 630.9, organic gardening has the number designation of 635.0484, and garden design is 712.

New non-fiction materials are located downstairs and the majority of the non-fiction collection is on the second floor. O’Fallon librarians have posted signs labeling each non-fiction shelf by number. Follow the signs to the topic areas that most interest you.

Feel free to ask for direction if you need it — the librarians are here to help you!

The general topic divisions are:

  • 000 Generalities
  • 100 Philosophy and psychology
  • 200 Religion
  • 300 Social sciences
  • 400 Language
  • 500 Natural sciences and mathematics
  • 600 Technology (Applied sciences)
  • 700 The arts
  • 800 Literature and rhetoric
  • 900 Geography and history

Potentially Sensitive Topics

To find the following sensitive topics, look for the number listed by category. You can also use the self-checkout machines for more privacy:

  • Abuse/Incest 362.76
  • Abusive relationships 158.2, 362.82, 362.88
  • Acne and skin care 646.72
  • Alcohol/drugs 362.29
  • Birth control 618.1
  • Body image 158.1, 306.4613
  • Dating 306.73, 646.77
  • Depression 616.8527
  • Divorce 306.89
  • Eating disorders 616.8526
  • Health and nutrition 613, 613.2
  • LGBTQ+ 306.76
  • Pregnancy 618.2
  • Sex 306.7, 613.9
  • Sexual health 618.1
  • Sexual violence 362.8292, 362.88
  • Suicide 362.2, 616.89

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