In the past, people have relied on trusted third parties to facilitate the transactions that define our lives: how we store medical records, how we share genomic information with scientists and drug companies, where we get our news, and how we communicate. Advances in distributed systems and cryptography allow us to eschew such parties. Today, we can create a global, irrefutable ledger of transactions, events, and diagnoses, such that rewriting history is computationally infeasible. What can we build on top of such a powerful data structure? What are the consequences of pseudo-legal contracts and promises written in mathematical ink? In this class, we will bring together experts in cryptography, healthcare, and distributed consensus with students across the university. The first weeks present a technical overview of block chain primitives. In the following weeks, the class will focus on discussing applications and policy issues through lectures and guest speakers from various domains across both academia and industry. Limited enrollment, subject to instructor approval.