The challenge to solve Apply Read the news alert from the prize announcement at the Blockchain for Social Good event in December 2017. The challenge is to develop scalable, efficient and high-impact decentralised solutions to social innovation challenges leveraging Distributed Ledger Technology (DLTs), such as the one used in blockchains. DLT in its public, open and permissionless forms is widely considered as a ground-breaking digital technology supporting decentralised methods for consensus reaching as well as sharing, storing and securing transactions and other data with fewer to no central intermediaries. In the wake of the widespread public attention for Bitcoin, several financial applications based on blockchains are already under development. The future is what we make it However, the potential of DLTs to generate positive social change by decentralising and disintermediating processes related to local or global sustainability challenges is still largely untapped. Examples of social innovations in which decentralised solutions based on DLTs have shown clear benefits over conventional centralised platform solutions include, but are not limited to: demonstrating the origin of raw materials or products and supporting fair trade and the fair monetisation of labour allowing for a greater visibility of public spending and a greater transparency of administrative and production processes participation in democratic decision-making by enabling accountability, rewarding of participation and/or anonymity enabling the development of decentralized social networks or clouds, or of decentralized platforms for the collaborative economy managing property, land registry or other public records contributing to financial inclusion This challenge is targeted at a wide range of actors: individuals, social entrepreneurs, civil society organisations, research centres from technological and social disciplines, creative industries, students, hackers, start-ups and SMEs. Tackling this challenge requires multidisciplinary expertise.