On June 23, 2016, the United Kingdom held a referendum on its membership in the European Union. Although most of Britain's establishment backed remaining in the EU, 52 percent of voters disagreed and handed a surprise victory to the "leave" campaign. Brexit, as the act of Britain exiting the EU has become known, is likely to occur in early 2019.The period since World War II has been marked by growing economic and cultural globalization and, in Europe, increasing political integration under the auspices of the European Union. Brexit marks a departure from this trend. For the United Kingdom, leaving the EU will mean withdrawing from the EU's supranational political institutions and will lead to the erection of new barriers to the exchange of goods, services, and people with the remaining 27 member states. More broadly, Brexit raises questions about the future stability of the EU and the extent to which further globalization is inevitable.This article discusses the economic consequences of Brexit and the lessons of Brexit for the future of European and global integration. I start by describing the options for post-Brexit relations between the United Kingdom and the European Union and then review studies of the likely economic effects of Brexit. The main conclusion of this literature is that Brexit will make the United Kingdom poorer than it would otherwise have been because it will lead to new barriers to trade and migration between the UK and the European Union. There is considerable uncertainty