Another country has rejected a new set of rules for the European Union, days after they were rejected by France.
People in the Netherlands voted against the European Constitution in the poll, which could mean it won't become law.
Nine countries have agreed to the rules so far, but all 25 EU members must vote for them before they are made legal.
The Constitution was meant to make it easier for countries to work together. Many people are against it because they say it makes them less independent.
Countries that have voted 'Yes'
'No' voters are also worried that the EU is expanding too quickly, and that the European currency, the Euro, isn't doing as well as it could.
Dutch Prime Minister Jan Peter Balkenende, who campaigned for a "Yes" vote, said he would respect the result of the vote.
The British government has said people in the UK will get to vote on the constitution next year, but because the Dutch have voted no, that might be delayed.