Module 3: Locating and Accessing Information

Classification Systems

A library classification system organizes material into subject categories or classes. There are two major classification systems used in libraries in the United States. The Dewey Decimal System is usually used in public libraries. The Library of Congress Classification System is primarily used in college and university libraries. It's characteristics include:

• 21 primary classes, or general subject areas, represented by letters (A-Z, excluding I,O,W,X and Y)
• This allows libraries to classify and arrange larger collections by the main subject matter
• The system further breaks these subjects into subclasses by the addition of one or two letters followed by numbers

Let's take a look at an example of how the Library of Congress System classifies the subject of education. The letter L represents this subject and is broken down as follows:

• LA History Education
• LB Theory and Practice of Education
• LC Special Aspects of Education
• LD Educational Institutions
• LH School Publications
• LT Textbooks

Each item in the library is given a unique call number based upon the Library of Congress classification system. The book What You Need to Know About Study Skills, classified in the LB subheading of education, would have the call number below. Each line tells us something about the book.

• LB is the Library of Congress subheading for the Theory and Practice of Education
• Material on Higher Education is placed between LB2300 and LB2430
• The third line represents the author or organization's name or the title of the work
• Some call numbers conclude with a publication date

On the next page we will look at how to find a book using a Library of Congress call number.