Pendaphonics is a tangible physical-digital-sonic environment and interactive system that engages users in individual, collaborative, group, and distributed interactive experiences. The development of this system, as an element of urban revitalization and as a transdisciplinary research endeavor, presents a strategy for the design and evaluation of a low-cost, flexible, distributed system for public interaction and performance in a large scale tangible system. Pendaphonics has been installed in a public new media arts space, where over 200 people experienced the initial opening of the environment, and is now active within five different research university interaction laboratories. This paper presents the development process and findings from observations and evaluation of Pendaphonics’ users and the social interaction patterns among performers and members of the public. In particular, the repeated and sustained invitation to interaction afforded by the cyclic motion of a pendulumâ€...