Crowdfunding is a popular fundraising system leveraged by several entrepreneurs to support their business, in particular start ups and SMEs. This research presents a first examination of social capital developed within crowdfunding platforms by the two main actors involved in this mechanism, namely the entrepreneurs and the investors. The research examines the impact of social capital of both these actors on funding success. We use several parameters in order to measure social capital and we collected data through Ulule, a well-known platform of reward-based crowdfunding. The results show that projects backed by entrepreneurs before the launch of their own project positively affect the funding success, while the projects followed by entrepreneurs have negative effects. Instead, projects followed by investors have a positive impact on funding success as well as the number of expert investors. The research will offer several implications for different stakeholders.