Timing data from piano performances of Gnossienne no. 5 are analyzed to examine the way in which a performer structures different subdivisions of a constant beat. The piece contains a wide variety of different beat divisions, and the timing data demonstrate that these rhythmic distinctions are accurately preserved by the performer. These data also provide the basis for a model of expressive rhythmic performance in which an underlying structural representation, consisting of rhythmic figures organized around a framework of beats, is transformed by an expressive system constrained by certain parameters. This accounts for the complex yet stable characteristics of musical performances by skilled exponents.