The National Theatre Museum of Slovenia was founded in 1952 under the aegis of the Slovene National Theatre in Ljubljana, to mark the 60th anniversary of the Provincial Theatre in Ljubljana.
The museum's first director was Janko Traven, who collected an enormous amount of material from the early periods of Slovene theatrical history. The museum was also supported by private donors. Janko Traven's successor Dušan Moravec began to organise the collected material more systematically, and in 1964 the museum began issuing various publications, including Letopis or The Repertoire of Slovene Theatres (to mark the 100th anniversary of Ljubljana Drama Society) and the magazine Documents of the Slovene Theatre Museum, which continues to be published biannually today. The Repertoire has been recently digitalised and included in the Sigledal.org - Slovene theatre portal.
In 1978 the Theatre Museum merged with the Film Museum to become the National Theatre and Film Museum, and in 1990 this institution acquired new display rooms and an office space at Mestni trg in Ljubljana's Old Town. However, in August 1996 the museum was divided into two independent institutions – the National Theatre Museum of Slovenia and the Slovenian Cinematheque.
The museum incorporates a library, an archive, a sound archive, a videotheque and an iconotheque. The videotheque collects, preserves and facilitates internal study access to recordings of theatre productions, while the iconotheque collects posters, costume design drafts, programmes, portraits, plans, and plans and photographs of theatre sets.
The National Theatre Museum of Slovenia Archive comprises personal documents, correspondence, legal and self-management acts, manuscript and typed texts, albums and collected newspaper reviews, plus thematically-arranged archive material on Slovene theatres, in particular legal and self-management acts, circulars, decrees and minutes of meetings. There is also a collection of articles relating to dramatic productions, opera, ballet, film, and experimental theatre covering the period 1963–1996 and a computer database of precisely catalogued premières in Slovene theatres from 1987–1995.
The museum organises various exhibitions at its premises or in other galleries. In 2006 it cooperated with Municipal Museum of Radovljica in preparing the Anton Tomaž Linhart Memorial Room.
In 2003 the museum organised the presentation of a costume from the Oedipus Rex production of the Slovene National Theatre Opera and Ballet Ljubljana at the Prague Quadrennial of Performance Design and Space (PQ) In 2011 the four authors are presented in Prague: Ema Kugler, Dunja Zupančič and Miha Turšič in the section Countries and Regions, curated by Tomaž Toporišič, while the Extreme Costume Design Section comprises also a costume from A Journey to Rome (Caravaggio) (produced by Slovene National Theatre Maribor) created by Belinda Radulović.
In the period 2008‐2011 the National Theatre Museum collaborated in a complex international project entitled Theatre Architecture in Central Europe (TACE), which received support of the Culture Programme of the European Commission. In spring 2009 Ljubljana hosted around 70 architecture students in an introductory workshop Visions and Possibilities organised by Vojteh Ravnikar's seminar at the Faculty of Architecture, University of Ljubljana. Afterwards the students developed their own visions of a potential new Slovene National Theatre building for the given location in the Ljubljana city centre with their tutors at their home universities (in Bratislava, Brno, Budapest, Gdańsk, Gliwice, Liberec, Ljubljana, and Prague). Later they revealed their ideas at an exhibition in Autumn 2009 at Ljubljana City Hall and in a catalogue.
In November 2009 a symposium on experimental theatre spaces was held in Ljubljana, followed by a publication Occupying Spaces. The extensive TACE exhibition Beyond Everydayness – Theatre Architecture in Central Europe that has toured Budapest, Prague, Warsaw, and Bratislava was hosted by the Museum of Architecture and Design in Ljubljana along with an accompanying publication synthesizing a pioneer research in the field of theatre architecture.