The Library of Congress is the United States' oldest federal cultural institution and serves as the research arm of Congress. It is also the largest library in the world. The LoC's collection of more than 130 million items includes more than 29 million cataloged books and other print materials in 460 languages; more than 58 million manuscripts; the largest rare book collection in North America; and the world's largest collection of legal materials, films, maps, sheet music and sound recordings.

The Library's mission is to make its resources available and useful to the Congress and the American people and to sustain and preserve a universal collection of knowledge and creativity for future generations. The Office of the Librarian is tasked to set policy and to direct and support programs and activities to accomplish the Library's mission.