While Michel Foucault's writings have been used in different branches of geography, his later writings on governmentality and especially biopolitics have not yet received due consideration within population geography. This paper attempts to divert attention to Foucault's writings on population, from his initial medical work to his later governmentality lectures on the regulation of national populations. From his various writings the different scales of biopolitics (subjective, territorial, geopolitical, state, international) and the different analytical levels (episteme, identity, visibility, techne, and ethos) appropriate to them are suggested as being of use to population geographers. Practical examples are given from research on colonial India due to its diversity and the foregrounding of political relations that can be observed there. A review of the debate on how to (re)theorise population geography is used to suggest that Foucault's writings can help population geographers to consider the objects, methods and outputs of their research in a critical and politically active way. Copyright © 2005 John Wiley & Sons, Ltd.