Why would anyone share their private car with a complete stranger? Why do others share a ride with people they have never met? Is it the need to save money what drives people's decision-making when sharing a car? or is it their belief in a more collaborative and responsible economy? Do they perceive any risk when sharing their possessions with others? These are some of the questions that the increasingly Sharing Economy has aroused in the last few years. With a special focus on Shared Mobility (car-sharing and ridesharing), the authors will try to shed some light on the factors that influence the users of these types of services in their decision-making process.