At a summit last weekend in Copenhagen, the European Union reached a historic agreement to add 10 new members. Expansion will nearly double the size of the union, but it only underscores a long-standing question: What is the ultimate goal of the EU? There is, as yet, no convincing answer.

The EU began enlargement negotiations with six countries four years ago; the number of potential applicants doubled a year later. They are Bulgaria, Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Romania, Slovenia and Slovakia. According to the agreement in Copenhagen, 10 of the countries are scheduled to join by May 1, 2004; Bulgaria and Romania would enter a few years later.

The key sticking point in entry negotiations was, as usual, money. All of the applicants are less developed than existing EU members -- some considerably so. Entry would constitute a financial burden on EU coffers. Poorer EU states worried that the new members would take funds that had previously been theirs. Accession entails considerable costs for new members as they adopt measures that bring them into compliance with EU norms. Their businesses are also likely to be less competitive in the single market. Last-minute negotiations endorsed extra funds for the new members and some front-loaded long-term assistance to cut the burden on the EU governments.