This paper steps into the minefield that is urban sustainability studies. It defends a rigorous definition of sustainable development called Environmental Space. This approach starts from the assumption that (1) there are limits to the biophysical capacity of the ecosystem and (2) that — within these limits — each individual has equal access rights to natural capital. On this basis, per capita sustainable consumption targets are calculated which can be (and are being) used as policy objectives. The paper explores how environmental space has influenced local sustainability politics in Edinburgh, Scotland. By doing so, it finds that environmental space targets are still far from being achieved. Reasons for this failure are investigated and Edinburgh's continued commitment to the material growth of her economy is identified as one key barrier. This point is illustrated through the investigation of recent policy decisions in Edinburgh which were justified as being necessary for growth, but which clearly contradict the aims of sustainable development.