An Introduction to the Dewey Decimal Classification System
An Introduction to the Dewey Decimal Classification System
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The Dewey Decimal classification system works similarly to the Library of Congress classification system and follows similar principles and patterns in a hierarchical format. Skillman Library is unusual in that it uses two classification systems instead of one. Here are examples of the Dewey Decimal call numbers:
The Dewey system is the oldest of the two classification systems, notice the call numbers are not consistent in format: some are bigger, some printed on labels and some handwritten directly on the cover.
Let's begin...
Question: How is the Dewey classification system different from the Library of Congress?
Answer: Dewey begins with numbers while the Library of Congress begins with letters. Dewey call numbers tend to only have two to three segments, whereas the Library of Congress tend to have four or more.
Dewey call numbers are arranged in numerical order in an ascending order based on the first segment.
Examples:
221 J43w comes before 222.9 .S65o
945.54 V344 comes before 945.6 .L122
If the numbers in the 1st segment are the same, continue on to the 2nd segment until there is a break in the pattern. Compared to the L.C. system, the Dewey system will have its alphanumeric line appear on the 2nd segment instead of the 3rd.
305.3 .S87br comes before 305.3 Y46
823.09 .B216888c comes before 823.09 B79122
Do you notice anything else different? The 2nd segment sometimes has a decimal point at the beginning and sometimes not. A decimal point is a mnemonic device to remind us that it's time to compare things on a digit-by-digit basis so a hierarchical sequence can be determined.
PRACTICE QUIZ #1
Which pair is correctly ordered?
1a) 257 .L4 1999 | 257. L4 2009
1b) 621 .Q4 A69 1947 | 621 .Q4 A19 1950
1c) 505.61 .S94 1968 | 050 .S94
1d) 031 .H83 1959 v.3 | 031 .H83 1928 no.3
Answer: 1a
Remember the phrase: “No-thing comes before something” in the previous L.C. tutorial?
This is where that phrase can really be handy when dealing with the Dewey Decimal system as space in-between digits can count towards determining which call number goes first. How would you place the call numbers in their proper sequential order below?
672 J22a
672 J22 Pr
672 J22x
The proper sequence should be:
672 J22..Pr
672 J22a
672 J22x
Since there is "no-thing" (highlighted in light blue) in between the "2" and "P", it precedes the call number that has the "a", followed by "x".
"A bound periodical is a book that contains previously published issues of a magazine or journal that have been bound together. Libraries bind periodicals into volumes when they are no longer current and place them on the shelves for reference." -University of Arkansas Libraries
Bound Periodicals and Indices
Bound Periodicals and Indices
When dealing with bound journals, you may encounter indices. A volume that is an "index" refers to a summary of topics within a particular series. It should be shelved at the end of a series it covers. See example below:
Take the Dewey Decimal sorting quiz here.
A score of 90% (40 pts) or better is passing,
you may take the quiz again to improve your score.
Take the Dewey Decimal sorting quiz here.
A score of 90% (40 pts) or better is passing,
you may take the quiz again to improve your score.
Updated 18 December 2025
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