The current mobility system relies heavily on privately owned cars, which results in high levels of emissions, material use, and use of scarce public space. Carsharing is a mobility innovation offering consumers on-demand, short-term access to cars. By changing consumption patterns and reducing car ownership, carsharing has great potential to contribute to a sustainability transition of the mobility system. Even so, carsharing only satisfies a small portion of today's mobility needs and has difficulties becoming mainstream. This study investigates the upscaling trajectory of carsharing in the Netherlands. We structure the analysis along the lines of the multilevel perspective and include economic, technological, sociocultural, and policy factors that shape carsharing growth. The results demonstrate how car ownership is entrenched in the social and economic fabric, and the specific barriers this poses to carsharing. Moreover, we find some forms of carsharing risk extending private car ownership rather than challenging it. The environmental outcomes of carsharing are not predetermined but depend on the trajectories key actors take during upscaling. Our analysis highlights the importance of studying innovations in the context of the consumption-production systems in which they emerge.