ROMANIAN JOURNAL OF EUROPEAN AFFAIRS Vol. 19, No. 2, December 2019 63 Common Interests and the Most Important Areas of Political Cooperation between Poland and Romania in the Context of the European Union Justyna Łapaj-Kucharska 1 Abstract: The article addresses several issues that constitute the main areas of Polish-Romanian relations in the 21 st century in the political dimension and in the broad sense of security. Relations between Poland and Romania have been characterized in the context of the membership of both countries in the European Union. Particular emphasis was placed on the period of the Romanian Presidency of the Council of EU, which lasted from January to the end of June 2019. The article indicates the most important common interests of both countries, the ways for their implementation, as well as potential opportunities for the development of bilateral and multilateral cooperation. The article also takes into account the key challenges that Poland and Romania must face in connection with EU membership. Keywords: Romania, Poland, European Union, Three Seas Initiative, multilateral cooperation. Introduction Polish-Romanian relations were particularly close in 1921-1939, when Romania was the only neighbour, apart from Latvia, who was Poland's ally. After the end of World War II, both Poland and Romania were in the Soviet bloc. After the collapse of the Soviet Union, Romania initiated, similarly to Poland, a political and economic integration to Western European structures, obtaining in 2004 membership in NATO and in 2007 in the structures of the European Union. The aim of this article is to point to the key areas of cooperation between Poland and Romania, with particular emphasis on the cooperation of these two countries in the context of the European Union. The article has been divided into several parts, according to their chronological order, in such a way as to identify the most important manifestations of bilateral and multilateral relations of our countries in particular stages: before Poland's and Romania's accession to the EU, from 2004 to 2010, and then in the second decade of the 21 st century. 1 Justyna Lapaj-Kucharska works at the Institute of Political Sciences and Journalism, Faculty of Social Sciences, University of Silesia in Katowice, Poland. She has a Ph.D. in social sciences in the field of political science. She is Assistant Professor at the Department of International Relations at the University of Silesia in Katowice. Her research interests revolve around Poland's foreign policy after 1989 in the European and non-European dimension as well as international relations in the 21 st century. E-mail: justyna.lapaj@us.edu.pl