ICZM depends on an understanding of the coastal zone system to be managed. During the SPICOSA project, the authors¿ task was to provide teams engaged in applications of the `Systems Approach Framework¿ with a theoretical basis for understanding these systems in terms of ecological, economic, and social structures and processes. This chapter briefly considers disciplinary approaches to conceptualizing coastal zones, and draws on these and the ideas of a number of twentieth-century thinkers, including Habermas, Luhmann, and Popper, to propose an interdisciplinary model of coastal `social¿ecological¿ systems. The model takes the form of a three-dimensional, animated object which can be seen at www.coastal-saf.eu. The use of the conceptual model is illustrated briefly in an application to a system in western Scotland which is losing its integrity under globalization.