With the responsibility of collecting materials comes the challenge of preserving them. For more than 200 years, the Library of Congress has preserved its books, photos, maps, manuscripts, recordings and other materials. Advanced techniques that were first developed at the Library are now in use around the world.

The Library's conservators oversee all types of treatment for materials, including chemical stabilization, physical treatment and restoration. They work not only with books and other paper collections but also with photographs, films and sound recordings. They also work to ensure that all collection materials are displayed, housed and stored under appropriate conditions.

Conservation staff members have also aided other institutions, both in the United States and abroad, in preserving their irreplaceable materials, and they have been exploring advanced materials for deacidifying books and other paper-based materials.

In 1969, the Library established its own motion picture conservation center and, since that time, has preserved in archival quality more than 15,000 motion pictures. The Library plans to open soon the most advanced preservation facility for audiovisual materials in the world, the National Audio-Visual Conservation Center in Culpeper, Virginia.