This paper derives a stochastic endogenous growth model to investigate the impact of European Union (EU) integration on convergence and productivity growth. The theoretical model implies both temporary and permanent positive effects of the integration process. The empirical part of the analysis uses structural break tests and data envelopment analysis to examine the accession process of five recent members to the EU15. The results show (i) endogenously identified accession dates as structural breaks, (ii) improved rates of productivity growth after accession over and above the Union benchmark level, and (iii) increased pace of overall growth due to capital accumulation as a result of institutional features of the Union such as Structural and Cohesion Funds. These findings support the theoretical model, implying that economic integration is beneficial for member countries, especially from a long-run perspective, and Cohesion and Structural funds help the new members catch up with the core-EU members' standard of living. (c) 2006 Elsevier B.V. All rights reserved.