We have developed a prototype of an integrated framework of tools, an MR application supporting a range of devices for collaborative multimodal interaction and individual expression. These tools allow groups of stakeholders in an urban project create and manipulate visual and auditory scenes, and mesh these scenes with the real environment of an urban planning site as an integral part of expressing and experiencing an evolving project. The technical infrastructure is housed in a specifically designed MR Tent (Figure 1), which allows bringing technologies that are normally available only in laboratory settings to the site of an urban project. On top of designing these tools in a user-centered design process, we have also developed an approach to supporting multiple interactions among the various agents (professionals, as well as lay people, referring to different temporal and spatial scales, representing various cultures) in real complex urban environments. We contend that when introducing participatory technologies, methods are needed that facilitate the constitution of multidisciplinary teams founded on public-private and local actors-global operators partnerships [Bourdin et al. 2006].