This paper focuses on the deployment of Geographical Information Systems (GIS) and Spatial Data Infrastructures (SDI) within local government in Thai Provinces. GIS has been used extensively within local government and many countries have undertaken SDI initiatives, but these tend to focus at the national level, failing to address the local deployment issues. By their nature as infrastructures, an SDI displays different diffusion patterns to GIS, as they exhibit network, externalities and extend an 'installed base'. Having described the GIS and SDI concepts, the authors subsequently turn to the Stage Model literature, which has been applied to generic Information Systems and GIS. An assimilation of this literature is presented and an extended model is proposed, which can be, applied in a prescribed manner, aiding in the deployment of GIS and SDI within local government..