In this paper, it is argued that over and above the three city sustainabilities of energy, society and economics, there is a fourth: creativity. It poses the question: can credible mechanisms be identified through which cities are more creative than other forms of settlement, as statistical evidence suggests ? It proposes that just as mechanisms can be identified linking the generic form of cities to ‘spatial sustainability’ for the first three, mechanisms can also be identified for creativity through the ways cities generates social networks. But whereas the first three sustainabilities are consequences of the form of the city, the fourth sustainability, creativity, is argued to be the reason for the form