When the leaders of the new 25-nation European Union pose for their next "family photo" at this weekend's summit in Dublin's Phoenix Park surrounded by 500 schoolchildren and a choir, even experienced diplomats will struggle to put names to some of the faces.
The unfamiliar figures in front of the EU flag will be a motley collection of the good, the bad and, in some cases, the ugly. On the one hand the EU will be welcoming the distinguished-looking Vaira Vike-Freiberga, the Latvian President, who spent her child- hood in a refugee camp in Germany. On the other it will be dealing with a Cypriot premier, Tassos Papadopoulos, who recently wrecked a deal to unit his island and allegedly had business links with Slobodan Milosevic.
One man who won't be there is Rolandas Paksas, Lithuania's flamboyant former president who once competed for the USSR aerobatics team, who was impeached earlier this month on corruption charges. The Polish Prime Minister, Leszek Miller, will be appearing in public on his last day in office, having tendered his resignation as of 2 May.
The arrival of 10 new member states will make the EU one of the world's biggest trading blocs, stretching from Galway to Gdansk, including a host of new energetic countries which are growing fast economically.
But this biggest and most dramatic of EU enlargements has been the most controversial. To the French, the former Warsaw Pact nations have shown an alarming tendency to see things through transatlantic eyes in terms of economic and foreign policy.
At an ill-tempered summit last year on the eve of the Iraq war, the French President, Jacques Chirac, berated the new nations for their backing of the United States and the UK. They had, he said, lost a golden opportunity to keep their mouths shut.
Poland's reputation as the most truculent new member of the club was confirmed in December when Warsaw dug in over the EU constitution, helping to cause the collapse of the talks.
These are predominantly poor member states and, with the exception of Poland (which is about the same size as Spain), are small nations. Most are new democracies, and of the 10 countries whose flags will be raised on Saturday alongside that of the EU, five did not appear on the map 15 years ago.
Inevitably these youthful political systems have proved unstable. Forced to take tough measures to qualify for EU membership, many of the governments have quickly become unpopular. As one EU official put it: "They have had to go through very painful measures and often the politicians have paid a high political price. There have been countries where the government was ousted by the opposition because they were pushing through unpopular economic reform, only to lose themselves in the subsequent election." Latvia has been through more than a dozen governments in a decade, and keeping pace with the revolving door of Eastern Bloc politics is a full-time job.
Of the seven men and three women nominated as European commissioners, six have served either as finance, foreign or European affairs ministers. The man nominated to take over from Mr Miller in Poland (though not yet approved by parliament) is a former finance minister.
The whiff of corruption hangs over the politics of many of the new nations. It was a financial scandal that helped to push Mr Miller to quit, although a court subsequently vindicated him.
Meanwhile, the EU will inherit a series of territorial and ethnic disputes. In a referendum earlier this month, Slovenians voted overwhelmingly to deny residence rights to thousands of people from other parts of the former Yugoslavia. These are known as the "erased" because they were removed from population records after Slovenia declared its independence in 1991.
The Czechs have had a long-running row with Germany over the Benes Decrees, the post-war declarations which deprived the Sudetenland Germans of citizenship and property rights. Relations with Austria have been only a little easier because of Vienna's safety fears about the Temelin nuclear power plant.
Meanwhile Budapest at one point tried to extend special rights and facilities to ethnic Hungarians living in neighbouring nations, including Slovakia.
The accession of the three Baltic nations has brought a large Russian-speaking population into the EU for the first time, with accompanying tensions with Moscow. And then there are the continuing problems of discrimination against an impoverished Roma minority.
But most of these problems have been helped by EU accession and there is little to suggest that they outweigh the benefits of enlargement.
The new member states may have their share of maverick politicians, but probably none of them stands out as much as Italy's premier, Silvio Berlusconi. Most are new democracies, but so were Spain, Portugal and Greece when they joined.
The pressure exerted by the struggle to be admitted to the EU has brought moderation to the flashpoints of Eastern Europe. Just as 30 years of co-operation in the EU has helped to smooth Anglo-Irish relations, so the Czech Republic now keeps Austria informed about developments at Temelin through a committee.
All countries have to match up to EU non-discrimination standards or risk being taken to court. Though the legacy of the Sudetenland problem remains, the political temperature has lowered. And Hungary's plans to promote the rights of its minorities abroad have been shelved.
This gets to the heart of European integration, which has entrenched democracy and tempered conflicts for 50 years. It is, says a diplomat from one new nation, "the goal of the whole exercise: to guarantee political and social stability".
President Papadopoulos is Europe's Mr Nasty after Greek Cypriots rejected EU-backed peace plan. Another black mark is his close financial ties to Slobodan Milosevic when he ruled Yugoslavia.
President. Centre-right nationalist, archetypal tough guy
Tensions with Germany over Czech refusal to apologise for kicking out Sudeten Germans at end of the Second World War. Austria pressing for closure of creaky Czech nuclear power station.
Prime Minister. Socialist, may be ejected at next election
Virtually recolonised by Sweden, which has helped with investment and EU entry. Like other members of the "New Europe" it resents French bullying and criticism of support for war on Iraq.
Prime Minister. Leads Res Publica party
Hungarians discriminate against the Roma minority. However, they are not actually persecuted, as in some of the other new member states. Sees Germany as most important strategic partner.
Prime Minister. Liberal, former Communist-era spy
In dispute with Lithuania over sea border. Grateful to UK and Ireland for not restricting entry to citizens looking for jobs. Major tensions with Russian minority, which comprises 30% of the population.
Prime Minister. Europe's first Green prime minister
Tensions over mistreatment of Polish and Russian minorities. Currently fuming at Latvia over pollution from a Latvian oil terminal helpfully positioned near the border.
Prime Minister. Soviet-era survivor
EU minnow (will be a good neighbour, with largest Man Utd fan club outside UK). But Maltese are sceptical about EU membership: it took a referendum and a general election to shoe-horn them in.
Prime Minister. Centre-right nationalist
Had a bitter dispute with France and Germany over Iraq war, then another when it helped to block the EU constitution along with Spain. Atlanticist outlook and strong ties with the UK.
Prime Minister. Social Democrat
Tensions with Austria and Germany over work restrictions for Slovak citizens - mostly Roma. But it treats these same Roma as second-class citizens, which is why many want to leave.
Prime Minister. Centre-right, fanatical marathon runner
Furious with ex-colonial master Austria for refusing to erect Slovenian language signposts in Carinthia province. Blotted its otherwise pristine copybook by "erasing" the rights of ethnic Serbs.
Prime Minister. Economist, leader of Liberal DemocratsReuse content