Mini Theatre, an Institute ('zavod') for promotion and execution of puppet and theatre performances, was founded as a small theatre from the youngest audience in 1999 by Robert Waltl, an actor, puppeteer, artistic manager and programmer. The company has a small hallat Ljubljana Castle where puppet theatre performances for children, youth and adults are presented, and school and kindergarten groups are invited to visit. The theatre performs also tours across Slovenia and abroad. A new theatre hall at Križevniška ulica in the old city centre of Ljubljana is currently under construction.

Mini Theatre stages about 400 performances in Slovenia and abroad annually. It produces also its own programme of puppetry performances of various genres and also contemporary theatre performances for youth and adults within its Post-drama Theatre section, working with Slovene and international stage directors and actors (R Waltl, Ivica Buljan, Philippe Calvario, etc). Next to staging of Slovene texts, contemporary world drama texts for adults are promoted. is In 2005 Mini Theatre collaborated with Wax Factory New York on a multimedia production called 'She Said...' with a soundtrack by Random Logic. In 2006 and 2007 its productions included Quartet by Heiner Mueller, Jackie by Elfride Jelinek and Mad About Vincent by Herve Guibert as well as five performances for children: Little Red Riding Hood by Brothers Grimm and Caliph Stork by Wilhelm Hauff, The Mishmash Bakery by the Slovenian poet Svetlana Makarovič, The Wishing Table by Brothers Grimm and Marek Becka and The Ugly Duckling by Hans Christian Andersen and Robert Waltl.

The Mini Theatre productions take part in numerous international festivals. The performances were performed in Italy, Austria, Serbia, Bosnia and Herzegovina, Croatia, Czech Republic, Hungary, Poland, Belgium, United Kingdom, Russia, Iran, Venezuela, Cuba, etc. They were awarded several festivals in Slovenia and abroad - in 2003 Mini Theatre got two prizes at the Borštnik Meeting, Slovene Theatre Festival, two awards at the Slovene Puppetry Biennial, as well as an award from the Slovene Drama Artists Association.

Behind the ancient walls of the Ljubljana castle, Mini Theatre organises the Summer Castle Afternoons. Besides the two festivals have been organised annually: the Mini Summer - International Festival for Children and since 2005 by Festival of Medieval and Renaissance Music.