Transportation patterns in big cities are redefined by the growing trend of car ownership and usage costs (e.g. the initial cost of buying a car, the constantly growing fuel prices, additional maintenance and insurance costs and the increased parking demand and time of travel). Under these circumstances, the demand for alternative vehicle-sharing transportation modes, such as carsharing or bikesharing, increases. Companies and authorities planning to develop such schemes need to know the factors driving their adoption, so that they can optimally position these services in a cost-effective way that will maximize their use. In this paper, the results of an on-line survey that was conducted in Greece, a country where carsharing is effectively non-existent and bikesharing is just emerging, are presented and analyzed. Given the nature of the survey and the fact that younger people are the most likely target audience for these services, the analysis focuses on data from the age group 1835 years old. A factor analysis of the advantages and disadvantages of car and bike-ownership is performed, so as to reveal any latent correlation between the different variables, while the factors affecting the adoption of carsharing and bikesharing schemes are analyzed descriptively. Ordered logit models capturing the willingness of the respondents to progressively join these schemes are also estimated. The model results suggest that respondents with annual income between 15 K and 25 K Euros are more likely to join carsharing or bikesharing systems when they become available in Greece. Carsharing is also expected to mainly attract people that use bus, trolley or tram for their commute, while bikesharing is more likely to attract those who go on foot. Age is also a significant determinant of joining bikesharing, with respondents in the 2635 years age group being more reluctant than younger ones. Finally, the more environmentally conscious the respondent declares that (s)he is, the more possible it is that (s)he will join one of the two schemes.