The paper examines the current position of the South Slavic languages within the European Union (Bulgarian, Slovenian, and Croatian) and discusses the future of the languages of the Central South Slavonic candidate states (Montenegrin, Serbian) and potential candidates (Bosnian) within the European language family. With the large expansion of the EU in relation to its founding, and thus the necessity of the existence of a large-scale translation infrastructure, the question of the sustainability of the principle of EU language equality arises. In this paper, we therefore investigate the issue of the status of South Slavic languages within the EU, and primarily the issue of the viability of the Serbian, Bosnian, Croatian and Montenegrin languages as official languages due to their extremely high degree of mutual similarity. Through a comparative historical analysis of the language-political situation in countries where these languages are official and a synchronic overview of contemporary language policies of individual states (Žanić 2007, Peti-Stantić 2013), the paper will confront ideas that problematize the status of Central South Slavonic languages within the framework of European integration. The language policy of the European Union was analyzed (Žanić 2004, Marić 2016), that is, the way it is implemented in practice and to what extent the slogan "United in Diversity" is valid. This analysis is completed by a comparison with other languages within the European Union that have a similar situation as the South Slavic languages.