Sharing economy is on everyone’s lips, while evidence on its actual development and its economic, social and environmental impacts is fairly scarce. The PeerSharing project, which is funded by the German Federal Ministry of Education and Research, therefore aims to specify and empirically explore the social-ecological effects and potentials of peer-to-peer sharing platforms. The main question of the research is, how sustainable is internet-based peer-to-peer sharing? The question is addressed at the example of selected platforms, available in Germany, in the areas of mobility (Drivy, flinc), accommodation (Wimdu) and clothing (Kleiderkreisel). A first inventory has shown that online peer-to-peer sharing comprises different sorts of platforms in various areas of consumption and develops very quickly. The PeerSharing project will explore empirically what chances and risks this dynamic development bears for a Green Economy.