On May 1st, 2004, Poland and 9 other countries became members of the European Union. The new economic and institutional conditions resulting from this event had a tremendous impact on Poland’s macroeconomic performance. Poland is the biggest beneficiary of the European Cohesion Policy in 2007-2013. This paper aims at evaluating the scope and strength of cohesion policy’s impact on the macroeconomic situation of Poland. Authors attempt to assess the economic benefits of Poland’s membership in the EU (focusing particularly on those related to impact of the cohesion policy’s implementation). Additionally, the article presents the benefits derived by the EU-15 countries from the implementation of the cohesion policy in Poland. Authors focus, inter alia, on assessing the impact of Poland’s membership in the European Union on macroeconomic situation of the country. The assessment of the said impact is based both on the analysis of selected studies of the subject and on authors’ own research based on available statistical data. Within such a context, authors discuss the results of three research projects – commissioned by the Polish Ministry of Regional Development – which attempt to evaluate the impact of the EU cohesion policy on selected macroeconomic indicators.