The difficulty of handling complex problems has spawned challenges to the traditional paradigm of technical rationality in design, planning, and policy making. One of the most frequently proposed solutions is an interdisciplinary approach, though few writers have described the operational dynamics of such an approach. A global model of interdisciplinary problem-solving is presented based on the premise that the unity of the interdisciplinary approach derives from the creation of an intermediary process that relies on common language, shared information, a mutual (...) sense of stakeholding, and the resolution of disciplinary differences. The theoretical underpinning of this approach is the conceptualization of interdisciplinary problem-solving as a communicative process that requires attention to the rhetorical and political dynamics of working with competing interests, practices, and disciplines. The practice portion is a composite picture of effective models, skills, activities, strategies, and techniques employed by actuals interdisciplinary teams. This global model offers a way of both theoretically and practically visualizing Th. K. van Lohuizen's ideal of achieving unity of town planning, an ideal that has profound implications for the organization of both professional practice and training. (shrink)