The aim of this paper is to outline a psychological approach to expression in music performance that could help to provide a solid foundation for teaching of expressive skills in music education. Drawing on previous research, I suggest that performance expression is best conceptualized as a multi-dimensional phenomenon consisting of five primary components: (a) Generative rules that function to clarify the musical structure; (b) Emotional expression that serves to convey intended emotions to listeners; (c) Random variations that reflect human limitations with regard to internal time-keeper variance and motor delays; (d) Motion principles that prescribe that some aspects of the performance (e.g., timing) should be shaped in accordance with patterns of biological motion; and (e) Stylistic unexpectedness that involves local deviations from performance conventions. An analysis of performance expression in terms of these five components - collectively referred to as the GERMS model – has important implications for research and teaching of music performance.