A rheological model of the Indian shield has been constructed using the thermal structure derived from available surface heat flow and heat generation data and the flow properties of characteristic minerals and rocks like quartz, diabase and olivine which respectively represent the upper crust, lower crust and upper mantle. Lateral variations in the thicknesses of the brittle and ductile crust and of the brittle upper mantle have thus been obtained for different tectonic environments. Implications of these results to interpretation of the seismic structure of the Indian shield have been pointed out.