Economic growth and competitiveness are usually analysed at the level of the national economy in traditional economic research. The problem of competitiveness within this line of thought is mainly regarded from the perspective of determining the sources of sustainable growth, which makes the economy more competitive than others. Competitiveness, therefore, is a multidimensional concept, which includes a range of factors, such as institutions, infrastructure, macroeconomic environment, market, human capital and technological development. Also, the process of joining the European Union significantly stimulates the development of the exact categories that are relevant for acceleration of the economic development. The aim of the paper is to assess the competitiveness of the candidate or potential candidate countries for membership in the European Union, through a comparative analysis of their competitiveness vis-à-vis EU countries. The results indicate that the competitiveness of the EU 15 countries, measured by Global Competitiveness Index and GDP per capita, is statistically significantly higher than the competitiveness of EU country group enlarged in the period 2004-2013, also compared to EU candidate or potential candidate countries. However, when it comes to the pillar of competitiveness related to the macroeconomic environment, according to the latest Global Competitiveness Report (2017-2018), the scores of the EU countries associated with enlargements in the period 2004-2013 are statistically significantly better than the EU 15 countries.