This article focuses on children's experiences of differences between improvising (i.e. creating spontaneous single-event performances) and composing (i.e. creating revised pieces). Eighteen self-selected children participated from a multi-ethnic, comprehensive Middle School in West London. Twenty-one weekly music-making sessions were conducted over a period of six months. A model mapping qualitatively different ways of experiencing improvisation and composition is presented using data drawn from the analysis of in-depth interviews, observation and recorded performances. The categories also form the arrangement of a model where improvising and composing are distinguished as being orientated towards (i) time, (ii) body, (iv) relations and (iv) space. These findings can be applied to the development of a pedagogy, which challenges some of the assumptions about what it is (and can be) to improvise and compose.