Carsharing is regarded to play an important part in the transition towards a more sustainable mobility system by changing how cars are used and transportation needs are met. Carsharing adopters own less cars, ride less car kilometers and depend on multiple transportation modes for their travel needs. There has been considerable interest in understanding the characteristics and motives of carsharing adopters. Yet, studies have been mostly limited to small-scale surveys, covering only specific cities or organizations and focusing on traditional B2C carsharing, disregarding the growing popularity of P2P carsharing through online platforms. This study contributes to extant research by investigating whether characteristics and motives differ between B2C and P2P carsharing adopters, and broadening the scope of the analysis to include an entire country (The Netherlands) and different carsharing provider types. First, our findings suggest that B2C and P2P carsharing adopters are rather similar in their characteristics but differ in the frequency in which they make use of carsharing and public transport. Second, we provide novel insights into the characteristics that influence a car owner to become an adopter of P2P carsharing as a provider. We find that car owners who already shared their car informally outside an online platform are also much more likely to provide their car through an online platform. We conclude with describing policy implications of our findings. Regulation should focus on shaping favorable conditions for a connected multi-modal transportation system instead of specific regulations for each carsharing business model.