Osor Musical Evenings are jointly organized by the association of the same name based in Osor and Zagreb and the Open University from Mali Lošinj. The cooperation between the Association and the local community dates back to the very beginning of the festival, from the second half of the 1970s. The current Board of Directors of the Association of Osor Musical Evenings, chaired by Lovro Marušić, consists of Martina Lipovac, Josip Nalis, Sanda Majurec, Branko Mihanović, Marin Marušić, Marija Saraga, Matko Marušić and Berislav Šipuš.
The first statute of the Association and the program goals of the festival were compiled by Vladimir Seljan, Ivo Horvatić, Stjepko Huml, led by Daniel Marušić, who was the spiritus movens of the festival until his death in 2009. Their call for a merger in the establishment of the new classical music festival was soon answered by Lošinj Sailing, led by director Ivo Jureković, and zlatko Stahuljak and Kazimir Brunović provided their professional assistance from the very beginning.
The first Artistic Council, founded in 1976, was chaired by Andro Mohorovičić and consisted of Stanko Horvat, Jasmina Juračić, Vojko Kiš, Vladimir Kranjčević, Rado Manzoni, Adalbert Markovic, Daniel Marušić, Miroslav Miletic, Zlatko Pibernik, Vida Ramuščak, Mladen Raukar, Vladimir Seljan and Zlatko Stahuljak.
Since 2011, when Osor Music Evenings were awarded the status of a national festival, the artistic director has been elected by the Ministry of Culture and Media of the Republic of Croatia, where the festival council is also active, whose task is to monitor and supervise the work of the festival.