Listening according to mood is likely to be what most people do when they listen to music. We want to take part in, or even be part of, the emerging world of the musical work. Using the sources of musical history and philosophy, Erik Wallrup explores this extremely vague and elusive phenomenon, which is held to be fundamental to musical hearing. Wallrup unfolds the untold musical history of the German word for ’mood’, Stimmung, which in the 19th century was abundant in the musical aesthetics of the German-Austrian sphere. Martin Heidegger’s much-discussed philosophy of Stimmung is introduced into the field of music, allowing Wallrup to realise fully the potential of the concept. Mood in music, or, to be more precise, musical attunement, should not be seen as a peculiar kind of emotionality, but that which constitutes fundamentally the relationship between listener and music. Exploring mood, or attunement, is indispensable for a thorough understanding of the act of listening to music.