The basis of this library is the personal collection of the late professor Dehkhoda. The deceased ordered his library books to be provided to the lexicon organization as long as the lexicon was in the process of publication. During the late Professor Dehkhoda’s life, the National Consultative Assembly offered some books to the organization. After the organization was transferred to the National Consultative Assembly, some of the deceased’s manuscripts were handed over to the Lexicon Library, and the rest remained in the possession of the deceased’s heirs. When the Lexicon was located at the National Consultative Assembly, some money was dedicated to buy books for this collection. The number of transferred books from Dehkhoda’s personal library was 1030 and the rest has been donated by the people interested in this institute. This is still the current procedure today. With donations of interested people’s collections to the Institute, it has become enriched. The major part of the collections has been precious books and in the form of lithography. The library is placed among the specialized Persian language and literature libraries. In addition to the compilers’ library, there is a language teaching center library in another section of the building for providing services to the foreign students. At first it was a small library, and gradually it turned into a bigger collection through buying books as well as donation cases. Shahidi Hall is another section of the complex established in 1386, when the late Dr Seyyed Jafar Shahidi donated his precious collection to the institute. The collection was merged into the library of the center and now they are a single unit. The mentioned collections have a computerized listing system connected to the comprehensive system of the Central library of University of Tehran and its sources can be searched from all units of the university. The library provides services to students and university professors, on condition of having a certificate.