This chapter considers how improvisers decide what to play, the creative process of improvising together, and the relationships between performing, composing, and improvising. In particular, it discusses similarities, differences, and relationships between performing, composing, and improvising. It considers how agency is experienced and executed by an individual while they are improvising with other people. A model is presented for the process of choice that any individual undertakes when taking part in improvisation, with detailed examples provided to illustrate how the model functions. Drawing on empirical qualitative evidence from post-idiomatic free improvisers, this chapter identifies a comprehensive set of options across this spectrum that any individual improviser may take over the course of a piece to allow the group to generate music. This model also offers a less daunting challenge to the novice improviser, and a potential way round a “block” for creative practitioners.