Urban sustainability has become an increasingly compelling issue for a human species that is now predominantly urban. Several contemporary influences are asserting the importance of urban action to achieve sustainability and improve species well-being generally: the new urban literature referenced as “urbanology”; powerful new urban coalitions like the C40 Cities Climate Leadership Group; and key international organizations, including the OECD, World Bank, and to a lesser extent UN-Habitat. From a critical social science perspective, it is apparent that, while avowing sustainability, these new urban assertions are freighted with, if not completely determined by, the assumptions and norms of neoliberalism, which progressive thought holds destructive to urban progress and well-being. We argue that these new and influential urban schemes and visions fail to comprehensively engage with the imperatives of critical social science, including debates about social equity, a failing human ecology and urban citizenship. The prospect of rapid continuing planetary urbanization, most of it irrevocably removed from the natural environment, suggests a need to rethink conventional approaches, institutional systems and the level of resources dedicated to human development in such crowded, dynamic spaces. Critical social science insists that these paradoxes and challenges are not merely systemic or technical but social in origin and solution. Moreover, we argue that the political questions that define socio-ecological trajectories require serious consideration. The human urban challenge raises the political ecology of change at the species level. Realization of sustainability requires a deep transformation of the structures underlying what is currently termed human progress. It is important therefore to critically appraise and challenge the new urban assertions that threaten to commit us to the disastrously failing path of neoliberalism.