Politicians in Northern Ireland, who have disagreed with each other for years, are starting to work together in a new power-sharing Assembly.
It means local decisions on things like education will be made by the Assembly instead of the British Government.
It's a big change because until now the two main parties, called the DUP and Sinn Fein, have disagreed so much they've been unable to work together.
A special ceremony marked the start of the Assembly at Stormont on Tuesday.
DUP leader the Rev Ian Paisley and Sinn Fein's Martin McGuinness, are the heads of the new administration.
The Reverend Ian Paisley and Gerry Adams agreed to share power in March
Speaking as the new First Minister of Northern Ireland, Mr Paisley said the Assembly was the start of a process to build a peaceful society.
"From the depths of my heart I can say to you today that I believe Northern Ireland has come to a time of peace, a time when hate will no longer rule."
There used to be a lot of violence in Northern Ireland because people were fighting about who should run the place and more than 2,000 people died as a result.
Ten years ago, a peace deal called the Good Friday Agreement saw the different parties agree Northern Ireland should have an Assembly.
But it stopped working in 2002 when the different parties accused each other of spying and said they couldn't trust each other.
The return of what's known as devolved government follows an important meeting in March between Ian Paisley and Sinn Fein president Gerry Adams, where they agreed to share power.
British Prime Minister Tony Blair said the decision to share power was very important for the people of Northern Ireland.