New application spaces and artistic forms can emerge whenusers are freed from constraints. In the general case ofhuman-computer interfaces, users are often confined to afixed location, severely limiting mobility. To overcome thisconstraint in the context of musical interaction, we presenta system to manage large-scale collaborative mobile audioenvironments, driven by user movement. Multiple participants navigate through physical space while sharing overlaid virtual elements. Each user is equipped with a mobilecomputing device, GPS receiver, orientation sensor, microphone, headphones, or various combinations of these technologies. We investigate methods of location tracking, wireless audio streaming, and state management between mobiledevices and centralized servers. The result is a system thatallows mobile users, with subjective 3-D audio rendering,to share virtual scenes. The audio elements of these scenescan be organized into large-scale spatial audio interfaces,thus allowing for immersive mobile performance, locativeaudio installations, and many new forms of collaborativesonic activity.