The Library of the Institute of Italian Encyclopedia was born together with the Institute itself in 1925. He was Giovanni Gentile, scientific director of the Encyclopedia, to provide it immediately to a rich private collection of encyclopedias and lexicons of the eighteenth and nineteenth centuries. Today, the number of volumes exceeds 130.000 units: the magazine sector includes 900 Italian and foreign newspapers. Among the special funds: the Aldo Santi Fund, Giacomini Fund, about the history of science and botany; Morelli Fund concerning pure sciences; Bontempelli Fund, for literature, consists of the volumes of the Library of novelist Bontempelli; Rafaele Contu Fund, history of science. The Library is open to scholars, researchers and teachers. Since 1988, the catalog is available online.