Mathis Wackernagel and William Rees describe the 'ecological footprint' (i.e. the ecological capacity, measured in hectares of biologically productive land, needed to supply a given person's consumption of natural resources and absorb their waste) as a conception of environmental sustainability, and have accumulated significant data to measure the footprints of nations, cities and even individual persons. Although the authors refrain from explicitly drawing normative inferences from their measurements, such implications lie not far beneath the surface of their work. Besides providing an empirical tool for assessing efforts to improve environmental performance, the footprint implies a normative ideal of global resource egalitarianism, once the conception is examined through the lens of contemporary political theory. In this article, I trace out the normative implications of ecological footprinting in comparison and contrast with those of carrying capacity, an alternative conception of sustainability which the footprint ought (or so I shall argue) to replace.