India, the population of which recently reached the one-billion mark, enjoys a rich and ancient census apparatus that remains an under-utilized source for the study of contemporary socio-spatial dynamics. Our paper summarizes the stages of a GIS project applied to the 75.000 localities of South India. The emergence of GIS technology in a country like India comes up against many scientific, technical or institutional problems. The georeferencing of villages, for instance, required considerable effort because of the unavailability of reliable printed maps. Similarly, systematic examination of the census data has underlined their shortcomings and called for corrections of all kinds. This article chronicles some of these concrete and theoretical difficulties, as well as solutions found to make the collected information available to a large number of potential users. By way of conclusion, we present some of the cartographic applications of this rich database, as well as some geostatistical tools that can be fruitfully applied in a renewed approach to the phenomenon of socio-spatial change. Illustrations given here come from various fields of interest: geography of Sabarimala pilgrimage, health care in Andhra Pradesh, impact of urbanization on Tamil villages, sexual discrimination in Tamil Nadu, irrigation in South India or spatial autocorrelation measurements.