Negotiations between the EU and the candidate countries in the Western Balkans have been dragging on for almost two decades. Until an official decision has been made on who can join the EU and when, actors at different levels have been working together within various programmes with the aim of advancing content-related harmonisation and fulfilling requirements for accession. In one of these programmes, Interreg ADRION, transnational cooperation plays an important supporting role for the possibility of Western Balkan countries to learn the practices and rules within EU projects. This thesis deals with the experiences of the project participants within this programme. Furthermore, the experiences are examined in terms of possible learning effects as well as the potential impact of Europeanization within the institutions and organisations of the programme members.