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 Researchers Home | Overview | General Collections | Special Formats | International

Collections Overview

The enormous size and variety of its collections make the Library of Congress the largest library in the world.

Containing approximately 142 million items in virtually all formats, languages, and subjects, these collections are the single most comprehensive accumulation of human expression ever assembled.  True to the Jeffersonian ideal, the collections are broad in scope, including research materials in more than 470 languages, more than 35 scripts, and many media.

The collections are constantly growing. Materials come to the Library through an acquisitions program that extends throughout the world and includes over fifteen thousand agreements with foreign governments and research institutions for the exchange of research materials; gifts; purchases; transfers from other U.S. government agencies; and copyright deposits. Each day about twenty-two thousand items arrive at the Library. Approximately ten thousand of these items will become part of the permanent collections, selected in accordance with the Library of Congress Collections Policy Statements which provide a plan for developing the collections and maintaining their existing strengths.

The Library's collection building activities cover virtually every discipline and field of study and include the entire range of different forms of publication and media for recording and storing knowledge. The Library has always striven to develop richly representative collections in all fields, except technical agriculture and clinical medicine, which are the collection responsibilities of the National Agricultural Library and the National Library of Medicine, respectively.

For nearly two centuries, the Library of Congress has relied first on its own expert staff, as well as on copyright depositors, book dealers, scholars, and other experts to assure that the national collections of the United States continue to enable the Library of Congress to fulfill its mission to "sustain and preserve a universal collection of knowledge and creativity for future generations."

All researchers must have a Library-issued Reader Identification Card to use any of the Library's public collections. All collections are stored in areas that are off-limits to the public and to staff without authorization. This "closed stack policy," like the reader identification program, ensures the security of the Library's collections. Researchers new to the Library are encouraged to take the "Research Orientation to the Library of Congress" course offered by the Humanities and Social Sciences Division. This 90-minute class, offered throughout the year, is a basic introduction for researchers using any of the Library of Congress collections and resources.