Dewey Decimal Classification

The resources in the library are arranged on the shelves or “classified” according to the Dewey Decimal Classification (DDC) system. The DDC is the world’s most widely used library classification system. The system is made up of ten main classes organised by disciplines or subject areas. All other subdivisions follow under each discipline. This means that each book will have its own unique number (called a call number or shelf number) and place on the shelf.

The book’s call number is on its spine and every number begins with three numbers (008 is never written as 8 in DDC), some have decimal numbers, and they are followed by various letters.

So why do some books have really long numbers? The longer the call number, the more specific the subject is. For example:

Management 658

Strategic Management 658.4012

Numbers to the left of the decimal point in DDC are whole numbers. Therefore 015 comes before 150. Numbers to the right are decimal numbers. Therefore 970.13 comes before 970.3. The letters are the first three letters of the author’s surname.

How DDC Classified Books are arranged on the Shelves:

The books are arranged on the shelves starting at 000 and increasing in number. When two books have the same call number they are arranged in alphabetical order according to the authors’ surnames.

How to read a DDC call number:

The best way to get used to DDC call numbers is to review and compare examples of books in different subject areas. Examples:

Linehan, M. et al (2002) International Human Resource Management & Expatriate Transfers: Irish Experiences. Dublin: Blackhall Publishing Ltd. Call number 658.309415 LIN

Guilding, Chris (2009) Accounting Essentials for Hospitality Managers. 2nd ed. London: Butterworth-Heinemann. Call number 657.837 GUI