Interview with Guy de Muyser, a diplomat in the Luxembourg Foreign Ministry from 1956 to 1969 and from 1981 to 1991, Secretary and Head of Cabinet of Grand Duke Jean from 1969 to 1981 and Marshal of the Grand Ducal Court from 1971 to 1981, carried out by the Centre Virtuel de la Connaissance sur l’Europe (CVCE) on 16 June 2009 in Luxembourg City. The interview was conducted by Christian Lekl, a Scientific Collaborator at the CVCE, and particularly focuses on the milestones in de Muyser’s diplomatic career, his role at the Grand Ducal Court and the development of Luxembourg diplomacy.