Research has investigated psychological processes in an attempt to explain how and why people appreciate music. Three programs of research have shed light on these processes. The first focuses on the appreciation of musical structure. The second investigates self-oriented responses to music, including music-evoked autobiographical memories, the reinforcement of a sense of self, and benefits to individual health and wellbeing. The third seeks to explain how music listeners become sensitive to the causal and contextual sources of music making, including the biomechanics of performance, knowledge of musicians and their intentions, and the cultural and historical context of music making. To date, these programs of research have been carried out with little interaction, and the third program has been omitted from most psychological enquiries into music appreciation. In this paper, we review evidence for these three forms of appreciation. The evidence reviewed acknowledges the enormous diversity in antecedents and causes of music appreciation across contexts, individuals, cultures, and historical periods. We identify the inputs and outputs of appreciation, propose processes that influence the forms that appreciation can take, and make predictions for future research. Evidence for source sensitivity is emphasized because the topic has been largely unacknowledged in previous discussions. This evidence implicates a set of unexplored processes that bring to mind causal and contextual details associated with music, and that shape our appreciation of music in important ways.