[3] As a national library it is the preeminent bibliographic repository of Mexico and is subject to legal deposit.

Its collection of 1,250,000 documents, including books, maps and recordings makes it one of the largest libraries in Mexico and Latin America.

Benito Juárez issued a decree on November 30, 1867, in which the National Library acquired most of its modern prerogatives, including legal deposit.

The Institute of Bibliographic Investigation [es] was established by the University in 1967 in order to facilitate the administration of the National Library.

The National Library moved to its current location in the UNAM campus of Ciudad Universitaria in 1979.