The European Union has long had a vested interest in fisheries and, consequently, in their management and conservation. It is therefore unsurprising that it has sought – and obtained – a status in a series of international organisations set up for this specific purpose and collectively known as regional fisheries management organisations (RFMOs). What is interesting, however, is that RFMOs are among the rare institutions in which the EU can enjoy full membership to the exclusion of its Member States. This specificity raises important institutional questions and leads to redefining the EU and Member State roles both externally and within the European legal order. Through analysis of the Union’s participation in RFMOs, this chapter aims to highlight the advantages as well as the limitations of the status that it enjoys in these organisations.