The fight against climate change, eco-responsible urban development and the control of energy consumption have emerged as pressing public issues on the southern coast of the Mediterranean over the past several decades. Politicians and public authorities as well as private actors, civil society organizations (NGOs and the voluntary sector) and international bodies present in the countries of this region have all engaged with these challenges, which are particularly pronounced in cities. As spaces, cities now account for the bulk of the population and energy consumption; and as complex systems of institutional and economic actors, they are highly sensitive loci for experiments in sustainable urban development (SUD). Subsequently, the methods, applications and adaptation measures required for meeting this new imperative have been under discussion since the early 2000s, if not earlier. The aim of this thematic issue is to examine the activities and projects underway to promote sustainable urban development, be it at the scale of one or several cities. Thus, our focus is not to describe the environmental vulnerability of Arab cities, nor to draw up an inventory of the national institutions responsible for sustainable development. Our study takes a critical look, both theoretical and political, and from different perspectives, at the key arguments and the various forms of mobilization.