The relations with the European Union (EU) began almost with the Mercosur’s creation. After signing a first framework agreement in 1995, the EU and Mercosur began negotiating a comprehensive interregional partnership with a free trade agreement since 1999. Negotiations were conducted with ups and downs, suspended, and resumed over a period of more than 20 years, and up to Mercosur’s 30th anniversary there is still no free trade agreement ratified with the EU. Based on the broad literature on the relations between the EU and Mercosur (both by European and Latin American authors) and on the analysis of official documents and declarations from the EU and Mercosur, this paper proposes some explanations as to why these negotiations have progressed so slowly and faced so many obstacles.