Lifelong learning, which the European Union especially attaches great importance to for social and economic cohesion, covers not only general and vocational education and training provided through formal and non-formal education, but also learning activities in all areas of life. As an important component of lifelong learning, adult learning includes educational activities designed to develop personal and professional skills and represents the participation of adults in lifelong learning. This study aimed to group the European Union countries in terms of adult learning within the scope of lifelong learning. Thus cluster analysis was performed using Wards and k-means clustering methods, resulting in the identification of four distinct clusters of countries. The analysis identified that Denmark, Estonia, Finland, Ireland, Luxembourg, the Netherlands, Spain, and Sweden are in Cluster 1; Belgium, the Czech Republic, Italy, Lithuania, Malta, Portugal, and Slovenia are in Cluster 2; Bulgaria, Croatia, Cyprus, Greece, Poland, and Romania are in Cluster 3; and Austria, France, Germany, Hungary, Latvia, and Slovakia are in Cluster 4. Additionally, by assessing the similarities and differences among the groups, it was determined that the countries vary in terms of variables of the participation rate in education and internet use for any learning activity.