How can built environment professionals use collaborative methods to expand, or at least maintain, their agency amid mounting pressures and volatile conditions? Across architecture, engineering, and planning, the contributions examine diverse modes of collaboration, unpacking the roles, organizational forms, and social settings involved while critically reflecting on the expectations placed on collaborative approaches. Taken together, they reveal a professional field in flux and show how urban future-making is increasingly shaped through different forms of boundary work among a wide range of actors, institutions, and sectors.