• Exchanging surplus copies with selected partners around the world. Surplus duplicates that the Library obtains are traded with U.S. educational institutions and with other selected exchange partners; LC has exchange arrangements with more than 12,000 institutions throughout the world;

• Receiving donations (some of which are solicited) of rare books, photographs, films, sound recordings, and manuscript collections; and

• Selecting surplus publications that are transferred to the Library from libraries in government agencies. Under long-standing policy, federal libraries are encouraged to transfer their surplus library material to LC, which has stipulated that it will accept from surplus only soft- or hard-bound books in certain categories.⁸

Two principles underlie the development of the collections: careful selection and stewardship. Selection has always been important in building LC’s collections, even though its mission is to acquire, organize, preserve, secure, and sustain—for the present and future use of the Congress and the nation—a comprehensive record of American history and creativity. The Library organizes its collections either by topical area or into special collections that are further subdivided by media or form of material (see Box 3.2). Selectors on the Library staff use their expertise in subjects, area studies, and special formats and their knowledge of LC’s collections to guide decisions about which materials should be added to the Library’s physical holdings. Once materials are selected for inclusion in the collections, the Library assumes a number of associated stewardship responsibilities that include preserving collections to ensure long-term viability and providing for intellectual access to materials. These responsibilities are discussed at length in Chapters 4 and 5.

The rapid growth of digital materials will challenge the Library in what it tries to collect, how it carries out its collecting role, and when and how it permits users to access its collections. Although there are many direct analogies between digital and physical collections, there are also significant differences. The digital era has brought with it a wide range of new types of intellectual creations and new means for authors to distribute their works. Some of the most important digital resources today