The purpose of this dissertation is to clarify the role of institutions for the development of car sharing services. Sustainable mobility has gained reasonable relevance in the past decade as it represents a fundamental aspect necessary for the preservation of the environment and for the improvement of the quality of life within urban centres. The use of private vehicles within cities has created numerous issues in terms of pollution and space consumption. The rise of the sharing economy and technological innovations have allowed the spread of new forms of shared mobility that aim at reducing private vehicle ownership. Despite the growing body of work produced by academics regarding the positive externalities that car sharing has on reducing emissions, traffic congestion and car ownership, the role of institutions as enablers and facilitators for the development of these services has remained widely unexplored. Following the development of a theoretical framework that draws on the work of academics that focused on the role of institutors, urban governance, and policy, the paper progresses by presenting four European case studies: London, Berlin, Rome and Milan. By identifying the key institutions and organizations that affect the development of car sharing, we then progress in listing and analysing the key policies and strategic plans that affect these services in each city. The analysis is supported by interviews carried out with eight experts that work in the sector. We then proceed in discussing and concluding that institutions play a central role in facilitating and directing the development of car sharing.