The article reveals the characteristics of think tanks as actors of the interest group politics in the European Union (EU). In this policy, they inspire public debate, conduct research, encourage new legislation and more effective public administration. A large number of European think tanks is engaged in interest group politics both at the national and supranational level of the EU governance, encouraging integration processes among the EU countries and Europeanization, which is the subject of analysis of this study. The strengthening of the role and importance of interest groups in EU policy is largely due to the increased power of the Union’s institutions, since the introduction of new legislation and regulation common to all EU countries leads to the feedback from various groups that represent both public and private interests. Obviously, these groups, when interacting with the power institutions of the EU, strive for the most effective protection of their interests. For this purpose their representatives hold meetings with officials of the European Commission and the European Parliament, as well as other structures of the Union. This interaction, aiming at promoting their interests by means of lobbying and advocacy, has been regulated since 2011 by the Transparency Register, jointly created by the European Commission and the European Parliament. The purpose of this study is to analyze the quantitative performance of think tanks in the EU and to develop on its basis the Ranking of EU countries, according to the level of Europeanization of the think tanks representing them. From the research methods perspective, the study is based on the matching of statistical data from the Transparency Register and the Global Go To Think Tank Index, which serves the basis for this Ranking. The study of the ranking makes it possible to identify groups of countries with a high, medium and low level of Europeanization of think tanks in all EU countries as of January 31, 2019. The results revealed on the basis of the analysis demonstrate the heterogeneous nature of the Europeanization process of think tanks in different EU countries.