During the years of 1806 to 1808, von Arnim helped gather the folk songs that made up Des Knaben Wunderhorn, the collaborative work of her brother and her future husband, Achim von Arnim. Some of the songs were later put to music by a number of composers, among them Gustav Mahler. The collection became a touchstone of the Romantic musical and poetic style. From 1808 to 1809 she studied voice, composition, and piano in Munich under Peter von Winter and Sebastian Bopp. She published her first song under the pseudonym Beans Beor, which she occasionally used later as well. Bettina sang briefly in the Berliner Singakademie and composed settings of Hellenistic poems by Amalie von Helvig.