Oton Župančič Library (Knjižnica Otona Župančiča) performs the tasks of regional library for central Slovenia. It was established in 1981 with the amalgamation of three libraries: the City Library (established in 1911 as the St Jacob Library by the Industry Society of St Jacob district), the Workers Library (established in 1926 by the Workers Chamber) and the Pionirska (Youth) Library (established in 1948). In Autumn 2006 these three original branches were united in a brand new six-storey building (each floor 1,000 square metres) at Kersnikova 2 in central Ljubljana. The Library also has three smaller branches in Ljubljana - Poljane Library, Nove Poljane Library and Kolodvor (Railway Station) Library - and has operated a mobile library since 1974; in 2007 a new bibiliobus was purchased.

With a registered membership of around 25,400, the Library contains 350,000 items. Its most important available databases are IUS INFO (all Slovene legal documents online) and IEFL Direct. As Slovenia’s most popular library, it has developed several information services, including the Stripoteka Collection of comics and the Mediatheque, which lends 440,000 items each year and includes a room for concerts and a special room for screenings. It also administers the Centre for Youth, the Pionirska - Centre for Youth Literature and Librarianship and the Centre for Self-Education for adults. The library offers a series of introductory IT courses for adults as one of its priority programmes. Other significant services include the ‘stock exchange’ of knowledge and the ‘stock exchange’ of jobs, and a home transport service for handicapped and old people. The library collaborates in the Kamra.si web project and prepares its own digital collection of texts.

The library also runs an exhibition programme at the new premises (eg an exhibition dedicated to Astrid Lindgren or Ita Rina in co-operation with Denmark and Sweden). From January 2008 the library houses the salon and study room dedicated to Oton Župančič (1878-1949), a significant Slovene writer and translator.

International activities include the international projects Calimera, Pulls, Tune, The Library as a Community Centre, PubliCA, Pulman (educational programme) and Let's Animate in Europe. Ljubljana Metropolitan Library is a member of the International Federation of Library Associations and Institutions (IFLA) and houses the office of the International Board on Books for Young People (IBBY), Slovenia.