It seems clear that, by a certain point in the twentieth century, the roles of composer and performer had become increasingly separated, but when we think of composers such as JS Bach, Beethoven and Rachmaninov, we are reminded that the idea of the musician as composer-performer is not new. Today, we can see an increasing number of musicians running a double life as composer and performer. What does it mean to be a composer-performer in the twenty-first century? How does the relationship of compositions to their performances change when the composer is the performer?