The emergence of cryptocurrencies and blockchain technologies is part of a broader wave of technologies that facilitate peer-to-peer (P2P) commerce, individualization of products, and flexibilization of production methods. Blockchain technologies aim to go one step farther. They organize P2P transactions and P2P information flows without companies that operate digital platforms. Cryptocurrencies are the first and therefore most developed application of blockchain technologies. Cryptocurrencies and blockchain technologies pose a range of policy challenges. They include the need to apply rules of financial oversight, consumer protection, and tax administration while at the same time encouraging and facilitating innovation, deal with the massive volume of electricity used to mine cryptocurrencies and determine whether governments and central banks can use blockchain technologies to improve their services. Policymakers should find a balance between curbing the hype and unleashing potentially transformational new opportunities.