A music librarian is a librarian that specializes in music. He or she deals with things pertaining to music collections and their development, preservation and maintenance, music literature, cataloging, and reference issues connected with musical works. Music librarians generally have an understanding of music history and music theory, and can also read music. A music librarian may organize lectures, classes, exhibits and concerts. They may also manage the inventory of rental music, or acquire materials from publishers for mail order and over-the-counter customers.