This chapter explores the relationship between music perception as it is studied in the laboratory and as it occurs in the real world. We first examine general principles by which listeners group musical tones into perceptual configurations, and how these principles are implemented in music composition and performance. We then show that, for certain types of configuration, the music as it is perceived can differ substantially from the music that is notated in the score, or as might be imagined from reading the score. Furthermore, there are striking differences between listeners in the perception of certain musical passages. Implications of these findings are discussed.