<p>This thesis examines contemporary approaches to live computer music, and the impact they have on the evolution of the composer performer. How do online resources and communities impact the design and creation of new musical interfaces used for live computer music? Can we use machine learning to augment and extend the expressive potential of a single live musician? How can these tools be integrated into ensembles of computer musicians? Given these tools, can we understand the computer musician within the traditional context of acoustic instrumentalists, or do we require new concepts and taxonomies? Lastly, how do audiences perceive and understand these new technologies, and what does this mean for the connection between musician and audience? The focus of the research presented in this dissertation examines the application of current computing technology towards furthering the field of live computer music. This field is diverse and rich, with individual live computer musicians developing custom instruments and unique modes of performance. This diversity leads to the development of new models of performance, and the evolution of established approaches to live instrumental music. This research was conducted in several parts. The first section examines how online communities are iteratively developing interfaces for computer music. Several case studies are presented as examples of how online communities are helping to drive new developments in musical interface design. This thesis also presents research into designing real-time interactive systems capable of creating a virtual model of an existing performer, that then allows the model’s output to be contextualized by a second performer’s live input. These systems allow for a solo live musician’s single action to be multiplied into many different, but contextually dependent, actions. Additionally, this thesis looks at contemporary approaches to local networked ensembles, the concept of shared social instruments, and the ways in which the previously described research can be used in these ensembles. The primary contributions of these efforts include (1) the development of several new open-source interfaces for live computer music, and the examination of the effect that online communities have on the evolution of musical interfaces; (2) the development of a novel approach to search based interactive musical agents; (3) examining how networked music ensembles can provided new forms of shared social instruments.</p>