This dissertation is about linking geographically referenced discussion contributions to spatial representations. The application background is the observations of procedures and software tools used in German land-use planning. In the view of planning as an argumentative process, support tools for group discussions and public participation are becoming increasingly needed. When people discuss spatial planning projects in a traditional paper-based procedure or with currently available computer support, e.g. in newsgroups in the World-Wide Web, the reference to geographic locations is only contained in the wording of contributions. This makes it difficult to analyze and assess the spatial references and their distribution over the planning area. The goal of this work is to initiate the development of computer tools that combine map representations with structured models of argumentation, labeled "Argumentation Map", short "Argumap". For the chosen setting of asynchronous, mediated communication via the Internet, some approaches use clickable hypermaps or Java mapping applets with graphical annotation facility. But none of these treats discussion contributions as individual objects with well-defined relations among them, to be linked to individual map elements. Representing documents on a map allows for efficient orientation, navigation, and retrieval of geo-referenced documents. Furthermore, on the base of an object-oriented model of geo-referenced argumentation, efficient exploration methods of geo-argumentative distribution can be realized. This dissertation introduces the foundations for such geographically enabled mediation systems. In order to achieve these findings, a simple class model has been developed that represents the essential entities of geo-referenced discussion, that is, a draft zoning plan consisting of plan elements, a discussion organized into argumentation elements, and spatial arguments that establish a relation between structured argumentation "space" and geographic space. Theoretical concepts for argumentative distance and topology between geographic objects have been derived from the class model as well as a set of practical use cases that helped to design a prototype demonstrator. This cursory implementation of an Argumap gives the researcher an impression of how visualization of attributes of argumentation elements, map elements and their linkage can be used to provide powerful navigation and analysis functions for stakeholders in spatial planning. In summary, this dissertation on the one hand contributes to the field of Geographic Information Systems (GIS) insofar it introduces geo-referenced arguments that could enrich many GIS applications, in participatory planning as well as in other domains. On the other hand, Argumaps add to the set of visualization methods of discussion support tools, whenever a discussion turns around a geographic or graphic design problem.