This chapter begins with a review of the single market's evolution to an increasingly integrated "domestic-like" market. It discusses approximation and mutual recognition, and explores some of the recent initiatives the European Union (EU) has undertaken to deepen the internal market. The chapter also explores criticisms being leveled at the internal market project. The economic rationale for the single market is based on a combination of benefits derived from expanding the size of the market: economies of scale, stronger competition, lower transaction costs, and better allocation of resources. The cumulative work of economists, lawyers, judges, and the public administrators tasked with implementing the single market has, for the most part, realized the bold ambitions laid out in the European Economic Community Treaty. The role of the mass media in undermining support for the single market has a focus of scrutiny after the Brexit vote.