Festivals are an important form of arts presentation and a significant tool for international co-operation. Every year a range of Slovene international festivals host professionals - artists as well as critics - from various artistic fields. Especially well known is the Vilenica International Writers’ Gathering, which has taken place since 1986 in a cave at Vilenica. The oldest is the Ljubljana International Biennial of Graphic Art, which since 1955 has showcased some of the most eminent artists from Europe, America and Asia. Other well-known international festivals include the BIO - Biennial of Industrial Design and the Ljubljana International Film Festival (LIFFe).

Ljubljana as a capital is undoubtedly the central site for festival activity, and its rich cultural life includes international festivals all year round. The traditional Ljubljana Summer Festival hosts the majority of well-known classical music performers and orchestras, while a high-quality programme of jazz music is offered at the Ljubljana Jazz Festival, and acclaimed world music groups are presented at the Druga Godba Festival, whilst the Ana Desetnica International Street Theatre Festival turns Ljubljana's streets into a spectacle. In the 1990s some important international festivals began as a result of non-governmental initiatives, for example the Exodos International Festival of Contemporary Performing Arts, the City of Women International Festival of Contemporary Arts with its focus on female creativity, the Ex Ponto International Festival which links former Yugoslav cultural initiatives, or the Break Festival, an international festival of young emerging artists. The Ljubljana Gay and Lesbian Film Festival began in 1984 and is as such the oldest gay and lesbian film festival in Europe.

Some important international festivals also take place in the regions - for instance the SEVIQC Brežice Festival, which takes place at about a dozen venues (including castles and monasteries) in the south east of Slovenia, or the Lent Festival in Maribor which presents around 400 events and attracts a great number of visitors. Jazz Cerkno Festival and the Izzven Jazz Festival, Maribor present high-quality international jazz and avant-garde music. Recently some new festivals have been initiated to celebrate a new trend or an intensive engagement in a certain art form. Kino OTOK - Isola Cinema Festival is a festival of non-American and non-European film hosted by the coastal town of Izola-Isola. Other examples include the DokMa International Film Festival and the International Festival of Computer Arts (IFCA), both held in Maribor. New artistic, cultural as well as social trends are discussed at the Memefest - International Festival of Radical Communication and Politically Incorrect Film Festival (PI-FF), while in the field of the creative industries the Magdalena International Festival of Creative Communication in Maribor is an important competitive platform for young designers.

In the year 2000 the 3rd Manifesta International Biennial of Contemporary Arts was held in Ljubljana under the title Borderline Syndrom, curated by four international curators. In the same year controversial film maker and painter Peter Greenaway created his 'Map to Paradise from Ljubljana', a fine art, sound and light installation at Ljubljana Castle. This complex site-specific project with accompanying publications and film retrospective was produced by the Muzeum Institute. Many international festivals, showcases and platforms have emerged from the independent cultural sector and numerous significant creative exchanges have been based on the engagement and initiatives of individual organisations. Currently, according to the statistics of the Ministry of Culture, non-governmental cultural organisations annually produce at least the same number of international co-operation projects as their counterparts in the state cultural sector, and consequently the number of potential partners for international co-operation in Slovenia is high. One signification network project is the Mladi levi Festival, conceived and produced annually by the Bunker Institute, which is a member of the European Junge Hunde Network. The 10th Young Lions Festival took place in Ljubljana in August 2007. The plenary meeting of the Informal European Theatre Meeting (IETM), one of the most significant performing arts networks in Europe, will be hosted by Ljubljana in 2008.