The Slovenian Theatre Institute (Slovenski gledališki inštitut) was founded in 2014 as the successor to the National Theatre Museum of Slovenia, which was founded in 1952. The institute is engaged in collecting, preserving, documenting, researching, interpreting, presenting and promoting Slovenian theatre culture, performing arts heritage as well as contemporary theatre practices, both at the national and international level.

The Institute houses material related to the Slovenian theatre history, organizes exhibitions and presents virtual exhibitions, publishes books form the theatre field, organizes various events (symposiums, round tables, lectures, etc.) and pedagogic activities (the institute is the national coordinator for arts and cultural education in the field of theatre, nominated by the Ministry of Culture of the Republic of Slovenia), houses theatre performances, etc.

In december 2013 it opened the permanent exhibition titled In pursuit of a theatre. From the jesuits to Cankar. The exhibition presents the beginnings and the main streamings of theatre in Slovenia, its integration into the European cultural context and its role in shaping the Slovenian national awareness. In 2017 on the occasion of the 150th anniversary of the Drama Society in Ljubljana the institute prepared a temporary exhibition About the Roads to »The Grandest Invention of Human Spirit« in Slovenia: Milestones in the Development of the Drama Society in Ljubljana.

The museum has organised various exhibitions also in other galleries. In 2006, it cooperated with the Municipal Museum of Radovljica in preparing the Anton Tomaž Linhart Memorial Room. In celebration of the Maribor Theatre Festival’s 50th anniversary in 2015, the Slovenian Theatre Institute in cooperation with the Maribor National Liberation Museum, the Slovene National Theatre Maribor and the Maribor Theatre Festival have prepared the exhibition Borštnik Bound!, which presented the beginning, the development and the atmosphere of the Festival, while simultaneously trying to catch the Zeitgeist by drawing parallels between the Festival events and the life of Maribor. The exhibition took place at the Maribor National Liberation Museum and in 2016 partially as well in Slovene National Theatre Nova Gorica. In 2016, on occasion of the 400th anniversary of William Shakespeare's death (1564-1616) the institute in cooperation with Cankarjev dom, Cultural and Congress Centre presented cultural and historical exhibition Hamlet in Slovenia. The exhibition was on display in Cankarjev dom and in 2018 partially also in Slovene Permanent Theatre in Trieste.  In 2018, on occasion of the 100th anniversary of Ivan Cankar's death (1876-1918) the institute cooperated by the exhibitions Ivan Cankar and Evropa in  Cankarjev dom, Cultural and Congress Centre and Ivan Cankar in City Museum of Ljubljana. In 2019 followed the first extensive retrospective exhibition of Slovenian scenography The Space within the Space: Scenography in Slovenia before 1991, which was set up by the institute in collaboration with the National Gallery of Slovenia, where it was on display. Latter the part of the exhibition was hosted by the Maribor Art Gallery (UGM) and the Maribor Theatre Festival at the UGM Studio.

The institute (or the museum up until 2014) has also been preparing  e-xhibitions since 2012. The first e-xhibition is called Alenka Bartl, Costume Designer and it digitally succeeded the exhibition of renowned costume designer Alenka Bartl at the National Gallery of Slovenia. Subsequently also the following e-xhibitions were prepared in collaboration with the Sigledal.org - Slovene theatre portal: Maribor Theatre Festival 2011, Maribor Theatre Festival 2012, Maribor Theatre Festival 2013, Maribor Theatre Festival 2014, the Borštnik Ring Award Winners, Slovenian Hamlets, About the Roads to“the Grandest Invention of Human Spirit” in Slovenia. At the same time the museum portal Museums offers a selection of institute's e-xhibitions: From our collections: Josip Primožič – Tošo, set-designer; Fran Milčinski, playwright; Miha Maleš: Portraits, Set design sketches by Milan Butina, the The Century of Ivan Cankar's Serfs, ...

In 2016–2021, the Institute operates the Gleda(l)išče project, which is designed as a sample model and a comprehensive strategy for flexible forms of teaching, which promotes partnerships between educational institutions and cultural institutions and creators, introducing informal, creative, and cultural and educational approaches into the formal teaching environment. The basic module of the project is the Golden Stick (Zlata paličica) platform, which provides a comprehensive web-based environment that lists recommended, high-quality theatre performances for children and youth and recommended arts and cultural education content in the field of theatre. The project is financed by the European Union from the European Social Fund and the Ministry of Culture of the Republic of Slovenia.

In the period between 2008 and 2010, the Institute (the Museum) cooperated with theatre institutes and museums from the Czech Republic, Hungary, Poland, and Slovakia as part of the Culture 2000. Together an ambitious international project TACE – Theatre Architecture in Central Europe was prepared. Between 2012 and 2017, the Institute (the Museum) cooperated with five museums from Austria, Denmark, Germany, Poland, and the United Kingdom to create the acknowledged traveling exhibition The History of Europe – Told by its Theatres under the patronage of the Association of Historic Theatres in Europe – Perspectiv and with the financial support of the EU Culture programme. Under Perspectiv, the Institute is also participating in the project The European Route of Historic Theatres.

The Institute is currently participating in several international projects. In 2019–2023 it is the leading partner in the EU (Creative Europe programme) supported project Classics in the Graphic Novel: A pilot model of new high school culture education through graphic novels with partners from Poland and Slovakia.