The distributed ledger problem is still far from understood. There is no consensus on basic definitions and assumptions of the models, which impedes progress in providing reliability guarantees. There are scaling problems, including the need to spend large amounts of energy, and the small transaction processing rate for current blockchain systems. Interestingly, solving these problems seems to require expertise from several diverse research areas including: cryptography, distributed computing, game theory and public policy. This workshop will bring together experts from these areas to establish and explore the theoretical foundations of Blockchain.