It is an international research collection of illustrated children's books, manuscripts, original artwork, prints, and educational toys from the 15th century to the present day, presented to the library by its owner, Lloyd E. Cotsen, in 1997. The collection has important holdings of materials in several languages, including English, Chinese, Czech, Dutch, French, German, Greek, Hebrew, Italian, Japanese, Latin and Russian.
Treasures include an early-Coptic Christian schoolbook; medieval manuscripts; scrapbooks from Hans Christian Andersen; drawings by Edward Lear, K.F.E. Freyhold, and Samuil Marshak; picture letters by Beatrix Potter; early editions of fairy tales by Madame d’Aulnoy, Charles Perrault, and the Brothers Grimm; a large collection of books published by John Newbery; Soviet Constructivist children's books; American dime novels; moveable books; jigsaw puzzles; educational playing cards; and other toys through the ages. It also houses the best collection of Japanese children's books outside of Japan (over 10,000 items), and of Chinese children's books outside of China (over 35,000 items).