The European Union's development has resulted in modifications of its institutional model. In the context of external activities, this refers to the distribution of formal competences on the one hand, and the functioning of European institutions in practice on the other, especially with regard to informal mechanisms. The aim of this article is to analyze the European Council's role in the formation of the European Union's external activities. The research questions address the sources and manifestations of the European Council's institutional dynamics in the field of external activities. The answers are based on an analysis of the European Council's behavior with regard to how the borders of the European project are established in relations with external partners. In terms of methodology, the text employs an analysis of the European Council Conclusions in the years 2011-2017.