With the arrival of 2007, Romania and Bulgaria joined the European Union, increasing its membership to 27 states. Simultaneously, Slovenia adopted the euro, Europe's single currency, becoming the first former communist state to do so and the 13th member of the euro-zone. The accession of Romania, with a population of 22 million, and Bulgaria, with a population with 7.7 million, has turned the EU into a common market with a total population to 489 million.

When French and Dutch voters rejected the proposed EU constitution in 2005, the EU appeared to have suffered a setback. But the entry of the two Black Sea neighbor countries shows that Europe's integration process is going on unhampered, although there wasn't much fanfare worldwide as happened at the time of the official launching of the euro on Jan. 1, 2002, or the EU's expansion into Eastern Europe in 2004.

In 2004, the EU embraced Poland, Hungary, the Czech Republic, the Slovak Republic, Estonia, Latvia, Lithuania and Slovenia -- all formerly of the communist bloc. These countries plus Cyprus and Malta, which also joined the EU that year, brought more than 100 million citizens to the EU. The accession of Romania and Bulgaria, which discarded communism in 1989 and applied for EU membership in 1995, means that the reunification of Western and Eastern Europe is nearly complete.

Both Romania and Bulgaria now can expect some 40 billion euro in EU funds to improve their infrastructure and industry. But the two countries face problems. While their economies are growing, their per capita income is about one-third of the EU average and they add only 1 percent to the EU's economic output. If they fail to make progress in reform, including fights against corruption and organized crime, they may see EU funds slashed.

Tangible efforts to integrate Europe after World War II materialized in 1951 when the European Coal and Steel Community was set up by France, West Germany, Italy, the Netherlands, Belgium and Luxembourg. In 1957, the six countries went further and signed the Treaties of Rome in 1957, creating the European Atomic Energy Community and the European Economic Community, accelerating efforts to form a common market through the removal of trade barriers.

The EU expanded with the accession of Britain, Denmark and Ireland in 1973, followed by the entry of Greece in 1981, Spain and Portugal in 1986, and Austria, Sweden and Finland in 1995. The EU has created a common market in which people, goods, services and capital move around freely, deepened cooperation among member states in such fields as defense, justice and home affairs, and integrated many member countries' currencies into one, the euro. It represents a large economic zone whose economic output surpasses that of the United States. The euro is quietly contesting the U.S. dollar's position as the main currency for foreign exchange reserves.

Now that Romania and Bulgaria have joined, the EU will likely take pause at its expansion. Some people and governments may not like to see new waves of immigration hit their countries. While the next strong candidate to join the EU is Turkey, there is persistent sentiment among many EU citizens against Turkey's becoming part of the EU. Opponents feel that Turkey, a Muslim country with a population of more than 70 million, is different from Christian Europe. The EU has suspended some of its membership talks with Turkey because of issues related to strained relations between Turkey and Cyprus.

For the time being, the EU will concentrate on improving its organization and management. The faces of EU leaders will also change. French President Jacques Chirac and British Prime Minister Tony Blair will soon disappear from the scene. A new French president will be chosen in elections set for April and May. Mr. Blair is likely to step down by summer.

2007 is an important year for the EU in a symbolic way. It is the 50th anniversary year of the Treaties of Rome. As Germany serves as EU chair for the first six months of the year, EU member states will renew their determination to further deepen European integration in a declaration to be issued in Berlin in March.

The big job for the EU is to resuscitate the process to adopt a European constitution. The Treaty of Nice, which took effect in 2003, governs how the EU institutions work. Since the treaty is based on the assumption that its members will number 27, new rules are necessary. The EU is likely to face difficulty in reviving the process to adopt a constitution.

Still, the fact that the EU exists as a community of nations bound by democratic rules in a region that was the scene of frequent wars should serve as an inspiration for Japan and other countries in East Asia, which are struggling to find common ground for close cooperation 61 years after World War II.