The call number of a book is its "address" in the library. The LCC call number is an alpha-numeric string and is unique for each book in our library. For example, the call number for Standards for Educational and Psychologic Testing by the American Psychological Association is LB3051 .A693 1985 and on the book's spine it may look like this:
The "LB" designates the LCC subclass of "Theory and Practice of Education."
The next number string helps identify the book. It may or may not include decimals. In this example, 3051 falls into the group 3050-3060.87--"Educational tests, measurements, evaluations, and examinations."
The third set of characters beginning with a period followed by a letter is the "Cutter Number" named after George Ammi Cutter and it typically identifies the author, but can also identify the title, publisher, etc. If there is more than one "Cutter Number," only the first number will begin with a period.
The fourth set of numbers is the year of publication. If the work is in more than one volume, there will be another number to indicate the volume number.
Most of us are familiar with the Dewey Decimal Classification System (DDC) used to organize and arrange books from our experience in our school and public libraries. However, most academic libraries use the Library of Congress Classification System (LCC). This system was developed by the Library of Congress to organize and arrange its vast holdings. The LCC system has 21 classes of information represented by letters of the alphabet. Most classes are divided into subsections with a two or three letter combination. For example, Class "L" is Education and it is divided into 10 subclasses such as "L" for General Education, "LA" for the History of Education, "LB" for Theory and Practice of Education, and so on.
The 21 Classes are shown below. Classes A-L can be found on the fourth floor, while M-Z can be found on the third floor of the HGLL.
For more information about the Classes and Subclasses, visit the Library of Congress Classification website.