 In 1949, he was appointed director of the Royal Conservatory in The Hague, a post he held until 1957.Between 1954 and 1962, he was appointed an Extraordinary Professor of Musicology at the Catholic University of Nijmegen.Andriessen's works included, besides eight masses, a setting of the Te Deum, four symphonies, variations for orchestra, lieder for voice and orchestra, chamber music, sonatas for cello and for piano, and works for solo organ.