This chapter focuses on the way European Union (EU) law regulates unfair commercial practices, that is, the behaviour of traders towards consumers as regards the marketing of goods and services. It presents a general overview of the main provisions of the UPCD, and takes into account relevant rulings by the CJEU on the interpretation of particular provisions. More than a decade has passed since the UCPD was adopted, and there is now considerable experience of how the Directive operates across the Member States. The chapter shows that there has been particular interest in the way the UCPD utilises the average consumer concept, but also recognises the needs of vulnerable consumers. An aspect of the directive which is likely to give rise to further debate is the relationship between the UCPD and the directives on consumer contract law, as well as the wider effect of the UCPD on national contract laws.