Systemic Improvisation refers to a class of musical improvisation systems, wherein virtual interacting agents transform the musical interactions between players. It is a new kind of musical interaction/situation/work, and a continuation of Dahlstedt’s and Nilssons’s long-term research into technology-mediated musical creativity and performance. The concept emerged from a previous research project, Creative Performance, which had a broader scope, investigating different categories of technologies that augmented and enabled musical performers to play in ways not previously possible. What we call systemic improvisation emerged as the most promising and interesting paths to follow in our continuing work, not least thanks to the very positive response from the participating musicians and the interesting musical results. In this project, we define an improvisation system as a system designed by someone, with a specific configuration of human agents (musicians) and virtual agents (interactive processes), and with communication going among all these agents, virtual and human. Systemic Improvisation is the activity of a number of musicians playing in such a system. It is also the term we have chosen for the whole category of musical works—a genre, if you wish. These improvisation systems work with all kinds of instruments, and the normal sound from the instrument is always heard acoustically, as in normal playing—it is not processed or hidden.