DEWEY? WE DO!
Decoding the mysteries of the
Dewey Decimal System.
SO MANY BOOKS!!
HOW DO I FIND THE
ONE I WANT?
Think of a room full of books. They’re not
in any order. Big ones and small ones,
paperbacks and hardcovers, a book about
dinosaurs next to a cookbook next to a
dictionary. It might be fun to browse
through a mess like that—but it would be
almost impossible if there were one
particular book you wanted to find.
In the late 1800s, a librarian named Melvil
Dewey developed a way to organize books in
a library so they’d be easier to find.
There are lots of subjects books can be
about. Some subjects have nothing in
common—like wolves and cookbooks. Others
are very similar—like flowers and trees.
Dewey grouped all the similar subjects together. He settled on ten
big groups of subjects. Then he assigned a number to those big
subjects. This first basic classification looks like this:
000 General Knowledge
Almanacs, Encyclopedias, Libraries, Museums, Newspapers ...
100 Psychology and Philosophy
Death & Dying, Ethics, Feelings, Logic, Making Friends, Optical Illusions, Superstitions ...
200 Religions and Mythology
Amish, Bible Stories, Buddhism, Christianity, Judaism, Islam, Quakers, and other world religions;
Greek, Roman and other myths...
300 Social Sciences and Folklore
Careers, Customs, Environment, Families, Folktales, Government, Manners, Money, Recycling ...
400 Languages and Grammar
Chinese, English, French, German, Italian, Japanese, Sign Language, Spanish. Includes
500 Math and Science
Animals, Biology, Chemistry, Dinosaurs, Fish, Geology, Insects, Physics, Planets, Plants ...
600 Medicine and Technology
Computers, Cookbooks, Engineering, Farming, Health, Human Body, Inventions, Manufacturing,
700 Arts & Recreation
Architecture, Crafts, Drawing, Games, Jokes, Music, Puppets, Songbooks, Sports ...
Children's Literature, Plays, Poetry, Shakespeare, Writing ...
900 Geography and History
Biographies, Countries, Native Americans, States, Travel, Wars ...
Then Dewey broke the big subjects down into smaller subjects
by dividing the big, “hundreds” numbers into smaller,
“tens” numbers. Similar subjects were assigned numbers
that were close together.
Library & information
030 General encyclopedias
040 Not used
050 General serial publications
080 General collections
090 Manuscripts & rare books
100 Philosophy & Pscyhology
120 Epistemology, causation, humankind
130 Paranormal phenomenon
140 Specific philosophical schools
Ancient, medieval, Oriental
190 Modern western philosophy
210 Philosophy & theory of religion
240 Christian moral & devotional theology
250 Christian orders & local church
260 Social & ecclesiastical theology
270 History of Christianity & Christian sects
280 Christian denominations
290 Comparative religion & other religions
300 Social Sciences
320 Political science
Public administration & military
360 Social programs & services
390 Customs, etiquette, folklore
420 English & Old English
Italian, Romanian, Rhaeto-
460 Spanish & Portuguese
490 Other languages
500 Natural Sciences & Math
550 Earth sciences
570 Life sciences
600 Technology & Applied Sciences
640 Home economics (cooking)
660 Chemical engineering
680 Manufacture for specific uses
700 Arts, Sports, Recreation
710 Civic & landscape art
730 Plastic arts (sculpture)
740 Drawing & decorative art
760 Graphic arts
Recreation, performing arts,
800 Literature & Rhetoric
820 English & Old English
850 Italian, Romanian
860 Spanish, Portuguese
890 Other literatures
900 Geography, History, Biography
910 Geography, travel
920 Biography, genealogy, insignia
930 Ancient world
970 North America
980 South America
990 Other areas
But even these divisions were not enough. For
instance, Mr. Dewey assigned the number 980 to the
continent of South America. But there are many
countries in that big continent. The system Mr. Dewey
designed was flexible enough to allow for a separate
number for different countries and regions:
980 General history of South America
986 Colombia & Ecuador
989 Paraguay & Uruguay
Mr. Dewey’s classification system allows librarians to
divide the numbers that are used to describe subjects
even further by using decimals—which is why we call it
the Dewey DECIMAL System.
For instance, 362 is the number assigned to social
problems. But there are all sorts of problems in
society. So the number is divided again:
362.1 Social aspects of health problems like
362.2 Social aspects of mental illness
362.4 Social aspects of physical disabilities
362.5 Poverty and homelessness
362.6 Social issues of the elderly
362.7 Social issues of children and teens
362.8 Social issues of families, including
Librarians can continue to create smaller and smaller
divisions using the decimal numbers.
For instance, 582.1 is the number for plants with seeds. But
there are different kinds of plants with seeds, such as trees
and flowers. So, in the Dewey Decimal System, there can be
slightly different numbers for flowers and trees:
Books about flowers and trees would be very close together on
a library shelf, because their Dewey numbers both begin with
“582.” But books about flowers would be right next to each
other, followed by books about trees a little further down
In really large libraries that have many, many books about
plants, the numbers could be even more specific: just for
oak trees, or just for roses, for example.
IS THERE A PAGE ABOUT LIBRARIES IN THE GUINNESS
BOOK OF WORLD RECORDS?
"Next Time Someone Asks You Where the 300s Are"
"Staff members at Northwestern University Library Cataloging Department
have identified what is believed to be the longest Dewey number ever
under serious consideration for assignment: a 23-digit monster for ARAB
ATTITUDES TOWARD ISRAEL by Yehoshafat Harkabi,
301.1543012917492705694. The meaning of the number can be broken
down as follows: 301-Sociology, 1543-Opinions, attitudes, beliefs on
specific topics (Add 001-999); 301-Sociology; 29-Historical and
geographical treatment (Add "areas"); 174-Region where specific racial,
ethnic, national groups predominate (Add from Table 5); 927-Arabs and
Maltese; 0-General relations between two countries (Add "areas"); 5694-
Palestine, Israel. In other words: Historical and geographical treatment of
opinions on countries where Arabs predominate, and their relations with
Sometimes it can be confusing to figure out how Dewey Decimal
Numbers work on the library shelves.
HINT: THINK MONEY!!!! AS IN DOLLARS AND CENTS!!!
A high percentage of books have Dewey numbers that just extend to
the hundredths place—two digits past the decimal point. This
makes the numbers look a lot like prices, without the dollar
So, if you aren’t sure whether 919.65 is shelved before or after
919.57, THINK MONEY. Which is larger, $919.65, or $919.57?
Remember that Dewey numbers get larger to your right and smaller
to your left when you’re standing in the stacks (which is what
librarians call shelving). So on the shelf, those two books will
look like this:
Here in the BMHS library media center, while we use the
Dewey Decimal System to organize our books and other
materials, we DO take a few liberties.
For example, some libraries designate biographies (books
about people’s lives) with 920; others with 921; others
with B. Here we use 92 for biographies.
Also, Mr. Dewey wasn’t really thinking about popular novels
when he created his system. He placed Fiction in with
Literature—the 800s. Most school and public libraries
choose not to do this. Here at BMHS, we use F or FIC to
In many school library media centers, there is another way the
Dewey Decimal System gets “tweaked.” There can be many books
on the same subject, like dinosaurs, or weather, or the American
Revolution. All these books would have the same Dewey Decimal
Number. And sometimes you don’t want just ANY book about
dinosaurs, you want the ones by Don Lessem. So printed just 567.9
below the Dewey number on the spine of the book (see Parts of a LES
Book tutorial) there are three letters: the first three letters
of the author’s last name. The combination of the Dewey
Decimal Number plus the letters makes up the book’s “call
Fiction works the same way: on the spine you’ll see F or FIC
on the top line, and the first three letters of the author’s
last name below. A novel by Walter Dean Myers has the “call
number” FIC MYE.
Biographies are a little different. In BMHS, the Dewey Decimal
Number is 92. The three letters below the 92 are the first
three letters of the SUBJECT’s last name, not the author’s.
So all the books about Eminem have the same call number: 92
EMI. And they’re right next to each other on the shelf. 92
The Dewey Decimal System is not the only way to
organize libraries. But it is the one used most often
in public and school libraries.
College and university libraries often choose the
Library of Congress system instead of Dewey. LC uses
combinations of letters instead of numbers to designate
subjects. Libraries that receive many documents from
the government, like copies of Congressional bills, use
a system called Superintendent of Documents. And
collections of musical recordings may be organized by
ANSCR, or the Alpha-Numeric for Classification of
Recordings, which uses combinations of letters to stand
for genres of music, like symphonies or opera or jazz.
Finally, always remember:
IF YOU NEED HELP FINDING
WHAT YOU’RE LOOKING FOR IN
THE LIBRARY, ASK A