Croatia is only the second of seven former Yugoslav republics to join the EU
Croatia is gearing up to become the 28th member of the European Union, with celebrations planned in Zagreb.
The milestone will occur at midnight, capping an extraordinary journey for the republic from the Balkan wars of the 1990s.
But after years in the economic doldrums, correspondents say few Croatians are in the mood to party.
The country of 4.4m is also joining a bloc deeply troubled and divided over its existing economic problems.
At midnight (22:00 GMT), EU signs will be unveiled at border crossings and customs duties will cease to be applied.
Celebrations will be held later on Sunday in the central square of the capital Zagreb, with speeches and music including Beethoven's Ode to Joy, the European anthem.
There will be addresses by officials including President Ivo Josipovic and European Commission President Jose Manuel Barroso - though German Chancellor Angela Merkel has pulled out of attending, saying she is busy, and the leaders of the UK and France will also be absent.
ConcernsThe only other former Yugoslav republic to have joined the EU since the break-up of the federation into seven is Slovenia.
But with one in five unemployed and Croatia's national debt officially classed as junk, many Croatians feel joining an economic bloc with its own profound troubles will do little to improve their prospects.
"Just look what's happening in Greece and Spain! Is this where we're headed?" asked pensioner Pavao Brkanovic in a Zagreb market.
"You need illusions to be joyful, but the illusions have long gone," he told Reuters news agency.
Concerns about Croatian corruption and organised crime remain in some EU capitals, and Croatia will not yet join the single currency nor the visa-free Schengen zone.
But advocates of EU membership say despite this, their case remains a persuasive one.
Two-thirds of Croatians voted in favour of accession last year - and the government points out it doesn't have a banking black hole like certain current EU members.
'Stability'"It's important for us primarily for the long term guarantees of political stability and then everything else - the single market too," Croatia's First Deputy Prime Minister, Vesna Pusic, told the BBC.
"But for us it's also the political stability and actually maybe that might sound a little over the top, but the fact that there was no war since it was formed and we actually know that there is an alternative to that which we've seen in our lifetimes," she said.
The EU itself has given Croatia a clean bill of health - and praised reforms which improve the rule of law and tackle corruption.
It hopes the other countries of the former Yugoslavia will be encouraged to join - and secure long-term peace for an historically turbulent region, reports the BBC's regional correspondent Guy De Launey.
Source: BBC News - Business http://www.bbc.co.uk/news/world-europe-23118035#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa
