Smithsonian Libraries and Archives is an institutional archives and library system comprising 21 branch libraries serving the various Smithsonian Institution museums and research centers. The Libraries and Archives serve Smithsonian Institution staff as well as the scholarly community and general public with information and reference support. Its collections number nearly 3 million volumes including 50,000 rare books and manuscripts.

The Libraries' collections focus primarily on science, art, history, culture, and museology. The archives include materials documenting the history of the 19 museums and galleries, the National Zoological Park, 9 research facilities, and the people of the Smithsonian. The Smithsonian Libraries and Archives is dedicated to advancing scientific and cultural understanding as well as preserving American heritage. The organization's Book Conservation Lab and other preservation efforts work to ensure long-term access to library and archival resources. Additional efforts include educational programs for learners of all ages, hosting internships and fellowships, and participating in collaborative projects such as the Biodiversity Heritage Library and the Digital Public Library of America.

Formerly two separate units within the Smithsonian, the Smithsonian Libraries and Smithsonian Institution Archives merged in 2020.

The Smithsonian Libraries promotes new ideas through knowledge sharing. We play a dynamic role in advancing scientific and cultural understanding and in preserving America's heritage. Our expert staff and extensive collections are a crucial resource for research and education communities at the Smithsonian, within the United States, and around the world.

The original library was founded by an Act of Congress on August 10, 1846, when the Smithsonian Institution was named a trust instrumentality of the United States. The Act created a Board of Regents for the Institution, and called for a building to house a museum with geological and mineralogical cabinets, a chemical laboratory, a gallery of art, lecture rooms, and a library.

The Smithsonian Libraries system as it exists today was not established until 1968, when Secretary S. Dillon Ripley realized that the existing library organization was greatly in need of an overhaul. He created a new position, Director of the Smithsonian Institution Libraries, and hired Russell Shank to fill the role. Shank reorganized the library staff and procedures, and created a modern, unified system with central services and a union catalog. By 1977, when Shank left, the quality and research value of the scientific collections were recognized nationally, and SIL was invited to join the Association of Research Libraries. SIL was granted a seat on the executive board of the Federal Libraries and Information Centers Coordinating Committee.

The late 1970s and 1980s also saw a growth in the number of Smithsonian Libraries branches, brought about by a range of donations to the Institution. In 1976, ten thousand rare scientific books and manuscripts were gifted to the Smithsonian by the Burndy Library, prompting the creation of the Dibner Library of the History of Science and Technology under the Smithsonian umbrella. Several years later, large donations of artifact collections led to the formation of new museums for subjects such as African art, American Indian culture and postal history and a new library branch was subsequently formed for each of these as well.

The 1990s introduced an expansion of the Libraries' focus to improve their ability to reach and educate the general public. The introduction of electronic and Internet technology played a large role in spurring this new outreach endeavor. In 1999, under the leadership of director Robert Maloy, Smithsonian Libraries staff completed a fourteen-year long effort to create a public access online catalog, with 97 percent of their then-holdings gaining digital records. The Smithsonian Research Information System (SIRIS) was introduced in the 2000s, providing the capability to search records of text, images, video and sound files from across the Smithsonian Institution.