EU leaders stressed in their welcoming messages that Croatia, the second country of the former Yugoslavia to join after Slovenia became an EU member in 2004, was a "role model" for the remaining countries of the Western Balkans.
Macedonia, Montenegro, Serbia, Bosnia and Herzegovina, Kosovo and Albania are in widely different stages on their way toward EU accession.
The EU summit found a compromise solution for the case of Serbia, which hoped to be granted candidate status during the EU summit. The main obstacle for Serbia is the normalisation of relations with its former province of Kosovo.
EU leaders gave Serbia a date for a possible decision for candidate status in February, depending on whether the Belgrade-Priština talks advance.
Regarding Montenegro, the EU Council decided that accession negotiation would be open in June 2012, conditional on progress in stepping up the reform of law enforcement and the fight against corruption and organised crime.
Together with Iceland, Montenegro appears to be the only country to have a chance to conduct accession negotiations in 2012. Turkey's accession negotiations are largely blocked, mainly due to the Cyprus issue.
Anecdotes to be remembered
EU leaders took turns signing Croatia's accession treaty, the first in alphabetical order being the a newcomer to EU summits, Belgian Prime Minister Elio Di Rupo, who was sworn in on Wednesday.
Also to be remembered is the wink by outgoing Slovenian Prime Minister Borut Pahor after his signature, interpreted by journalists from the region as a reminder that a maritime border dispute between the two countries has yet to be solved with Croatia.
Croatia is now due to join the EU on 1 July 2013.
There was also speculation over the absence of French President Nicolas Sarkozy at the signing ceremony. State Secretary for European Affairs Jean Leonetti signed the treaty on behalf of France. The incident sparked a buzz on Twitter and the Croatian press interpreted Sarkozy's snub as part of his strategy to please a home electorate wary of further EU enlargement.
Asked whether Sarkozy intentionally skipped the ceremony, Croatian President Ivo Josipović said that according to his information, constitutionally the French president could not sign treaties in the absence of his prime minister. French Prime Minister François Fillon usually doesn't attend EU summits.
EurActiv asked the European Commission, the guardian of the EU treaties, whether other treaties had not been signed by the French president. A diplomatic answer read that EU countries were free to decide who is entitled to sign on their behalf.
Another peculiarity rested on the number of press conferences given by Croatia.
The Balkan state delegation gave two briefings to journalists – one by outgoing Prime Minister Jadranka Kosor, whose centre-right HDZ party lost the elections held on Sunday, and another one by President Ivo Josipović, who is from the ranks of the Social Democratic Party of Croatia.
Asked to comment if this reflected the uneasy relations between them, Josipović insisted that the two had different programmes.
Kosor told journalists that she signed the accession treaty with a pen offered to her by Pope Benedict XVI. Croatia is a Roman Catholic country and part of the antagonism over the Serbo-Croatia wars of 1991-1995 was the divide between Orthodox Serbs and Catholic Croats.
In her speech, Kosor made reference to the heroes of this war, a sensitive issue, as some of those "heroes" have been indicted for war crimes by the International Criminal Tribunal for the former Yugoslavia.