The fragmented academic literature on sharing modes of provision deals with a diversity of initiatives ranging from for-profit business models to commoning initiatives. This literature mainly deals with individual instances, implicitly assuming that the sharing economy comes about by multiplying such initiatives. In this paper we argue that the transition to a sharing economy is a process where sharing and non-sharing modes of provision interact, constituting a complex process of social change. To facilitate research, we provide a literature review of the variegated literature, and develop a conceptualisation of the process of transition to a sharing economy using ecosystem thinking. In addition, we propose an approach to assess the environmental impact of sharing business models that takes the system context into account. This conceptual work is illustrated with the case of personal mobility. This work allows us to define a focused research agenda for researchers interested in the innovation and diffusion of sharing modes of provision as part of the wider transition to a sharing economy.