Geographical information Systems (GIS) provide tools for manipulating and analysing the large thematic datasets associated with Gondwana research. We have used a customised version of Environmental Systems Research Institute's ArcGIS, version 8.2, as the basis of our 'Gondwana and Southern Ocean Computer Model' (GSCM). The additional functionality necessary for paleogeographic work was written in Visual Basic for Applications (VBA), and includes routines for assigning data to the relevant plates (Plate Sieving) and transformation from present to paleo-coordinates (Rotate Data). The sieving function employs a user-supplied plate network, so that the same data can be assigned to different plate systems at different scales. Paleo-coordinate transformations are handled entirely within ArcGIS, preserving the links to data attributes, and thereby permitting spatial analysis with continents in their former configuration. We give a detailed description of these functions, together with some simple examples of the system's capabilities using data to large igneous provinces.