This was the biggest EU enlargement ever and a historic step towards unifying Europe after decades of Cold War division.

At the time, some of the 15 existing EU countries were worried about the impact the new members would have on their economies and social systems. But five years later a study by the commission shows that those fears were unfounded and that expansion has been a win-win situation for member countries new and old.

The expansion has contributed to significant improvements of living standards in new member countries, to modernisation of their economies and to more stabilised institutions and laws. It has also created new investment and export opportunities for enterprises in old member countries. And the whole EU has benefited from increased trade between members, becoming more competitive.

Rapid integration brought incentives for growth. In some new member countries, however, it also created vulnerabilities that have been aggravated by the current global recession. But the EU has the tools to respond to the crisis. The EU’s stability and growth pact and jobs and growth strategy promote sound public finances and structural reforms. In addition, the EU provides financial support from the structural and cohesion funds, European Investment Bank and the EU's balance of payments facility.

Looking ahead, the commission notes that the economic slowdown may offer opportunities for deep, growth-enhancing policy reforms – essential to promote continued integration, close gaps in income, ensure a prominent role for the EU in the global economy and help it welcome new members in future.