The European Territorial Cooperation programme (Interreg) is a long-standing instrument of EU cohesion policy aimed at encouraging economic growth in border areas. According to a report from the European Court of Auditors (ECA), the cooperation programmes financed through Interreg had clear strategies for tackling existing cross-border challenges. However, several weaknesses in the implementation of the Interreg programmes and in their monitoring limited the potential to unlock the capacity of the adjacent regions they covered.Interreg’s total budget for the 2014-2020 programme period was €10.1 billion. Over €6 billion was used to finance projects associated with internal borders.