 From 1998 to 2001 he was head of the Guardini Foundation, from 2004 to 2011 head of the advisory committee for music.From 1999 to 2003 Schlee was Vice General Manager of the International Beethoven Festival in Bonn.After this he was General Manager of the Carinthischer Sommer from 2004 to 2015 as well as a member of the university committee of the Mozarteum Salzburg (2008-2013).