A model is presented for representing and generating piano performance. The model has far fewer parameters than the number of notes. This model explicitly addresses one of the fundamental characteristic of music performance that different areas in a performance have very different kinds of objectives or strategies that are employed. A graphical model is introduced to represent the evolution of the discrete strategies and tempo and dynamic progression. We design interactive procedures that allow users to modify the model intuitively. An algorithm is described to estimate parameters from partial performances that represent the skeleton of the music. Experiments are presented on the two-piano version of Rhapsody in Blue by George Gershwin.