Smart Cities is a rapidly growing concept in both research and policy practice. It is viewed as a solution for cities to better cope with key societal challenges like energy transition, mobility and social innovation. Smart Cities make extensive and effective use of big data and IT, and employ smart incentives to encourage small-scale and efficient solutions for energy and mobility. This, in turn, calls for new modes of – smart – governance, with the active involvement of a wide diversity of public, private and citizens’ organizations. ‘Smartening’ cities enables them to exploit their potential both socially (self-organizing city) as well as technically (self-steering city).