Poles have voted to join the European Union by a large margin, according to preliminary results from this weekend's referendum.
Voting picked up on Sunday
About 77.5% have said yes to the EU, with a turnout of around 59%, according to initial results.
At least 50% turnout was needed for the referendum to be valid.
President Aleksander Kwasniewski hailed the result, telling cheering crowds in Warsaw: "We have returned to the European family".
The result is heartening news for the unpopular government of Prime Minister Leszek Miller that staked all on this single issue, the BBC's Nicholas Walton reports from Warsaw.
A great, proud nation is turning the page of a tragic century and freely takes the seat that should have belonged to it right from the start of the process of European integration
Mr Miller immediately called for a vote of confidence in his minority government, and announced plans to overhaul the tax system.
Poland is the largest of 10 mostly Eastern European countries due to join the EU next year, with more citizens than all the others combined.
The European Commission hailed the result as a turning point in European history.
"A great, proud nation is turning the page of a tragic century and freely takes the seat that should have belonged to it right from the start of the process of European integration," it said in a statement.
Polish-born Pope John Paul II, who had backed a Yes vote, said on Monday he hoped the result would benefit both his native country and the EU.
"The Holy Father hopes that... Poland can make a contribution with its moral and spiritual values and its religious convictions," said Vatican spokesman Joaquin Navarro-Valls.
There had been fears that the two-day referendum might be invalidated following Saturday's low turnout - when only 17.61% of registered voters cast their ballots.
But on Sunday voting picked up, as many churchgoers in the mainly Roman Catholic country went from mass to the polling booths.
Turnout was reported higher in cities like the capital Warsaw, where authorities had offered free museum tickets to dissuade people from leaving during the weekend.
But in villages, some voters openly showed their opposition to EU membership.
"They are threatening us with Brussels, which is not willing to give anything to farmers and our living is hard," Stanislaw Lach, 74, a retired farmer, said.
"My pension is 600 zlotys ($160) and if we join the European Union all prices, starting with electricity and bread, will increase," another pensioner said.
Many Polish voters are openly cynical about politics, with the country's economy in serious trouble and a government that has been criticised as ineffective and tainted by corruption scandals, our Warsaw correspondent says.
A leading film producer, Lew Rywin, was charged over the weekend for his part in a scandal involving allegations of bribery at the heart of government.
Mr Miller himself is under investigation. He has testified to a parliamentary committee of inquiry, and is scheduled to appear again later this month.
Poland's size means it will have the same weight as Spain in EU votes, behind the UK, France and Germany.
Of the 10 countries due to join the EU in 2004, six have now held successful referendums.
The Czech Republic is to follow this weekend, with Latvia and Estonia due to hold votes in September. Cyprus has no plans for a referendum.
Poland's final result is expected at 2000 (1800 GMT).