It is a familiar experience to most of us that we can rehearse musical pieces in our minds although there is no auditory musical stimulus. This subjective experience is an example of musical imagery. Research into cognitive psychology has shown that mental imagery is not only a subjective experience, but a measurable cognitive phenomenon as well. Neisser clarifies the nature of mental imagery as a cognitive phenomenon: 'If memory and perception are the two key branches of cognitive psychology, the study of imagery stands precisely at their intersection' (Neisser, 1972, p. 233). This statement is confirmed by the fact that most research into mental imagery has focused on the similarities between mental imagery and perception, but today an increasing number of studies also concentrate on mental imagery and cognition. The latter approach studies the role of long-term memory, interpretation, learning and conceptual knowledge in mental imagery, or investigates mental images as activated short-term memory or working memory representations. In this chapter, I first discuss the nature of musical images, and then ask to what extent the concept of working memory applies to musical imagery.