The purpose of this article is to show Poland’s path to European Union membership from the perspective of the 20th anniversary of the signing of the Accession Treaty. Joining the Community was proceeded by many years of preparation and efforts. Poland had to meet many necessary requirements to finally join the ranks of the member states. The negotiations, which began on April 3, 1998, were concluded on April 16, 2003, with the signing of the Accession Treaty in Athens. In Poland, the decision was also decided by the public expressing its opinion in a referendum held on June 7–8, 2003. On July 23, 2003 the Accession Treaty was ratified, and on May 1, 2004. Poland became a member of the European Union. Poland’s entry into the European Union made it possible to take a civilizational step. Poland benefited from its presence in the EU in many dimensions, primarily political, economic and social. The benefits of Poland’s accession to the EU far outweigh the costs. This assessment is also confirmed by the opinions of citizens expressed in surveys. In June 2022, the number of supporters of Poland’s EU membership reached a record 92%.