The SDLP is undergoing a process of radical change, the party's leader, Mr Mark Durkan, said last night.
He told SDLP activists in Belfast the party must persuade the Irish people that its vision of a united Ireland "holds out the guarantee of permanent peace, economic growth and an inclusive and fair society".
He unveiled a new SDLP logo, replacing the traditional green and red one.
The new design by Mr Paul Martin, who has also created symbols for Fianna Fáil and the Green Party, consists of three swirls forming the shape of a shamrock.
Each swirl is a different colour - green symbolising nationalism; red for socialism; and orange for the unionist tradition.
The SDLP's revamp follows Mr Durkan and Ms Bríd Rodgers taking over the leadership and deputy leadership from Mr John Hume and Mr Séamus Mallon eight months ago.
Sinn Féin overtook the SDLP as the largest nationalist party at last year's Westminster and local government elections.
In his address, Mr Durkan said people had lost faith not in the Belfast agreement but in the capacity of the political parties to fulfil its potential.
"There are some parties who are for all of the agreement some of the time.
"And there are some parties who are for some of the agreement all of the time.
"But the SDLP is for all of the agreement all of the time for all of the people," he said.
The SDLP had pioneered the agreement's key concepts, he said.
"Let us celebrate the outstanding achievement of those who founded and led the SDLP over the past generation that brought a community from grievance to governance."
The SDLP's goal was to "unite the island and its people", Mr Durkan said.
"It is that outstanding goal we must still pursue . . . We seek a united Ireland that is confident, pluralist, and non-sectarian. One that can find the magnanimity to offer a home not only to those who are Irish, but also to those among us who are British.
"One that is unafraid of differing identities and allegiances. One that is determined to combat sectarianism in the North, and racism in the South."
The SDLP was undergoing a period of radical change, he said.
"Behind us is a legacy of achievement and delivery.
"Ahead of us lie new challenges and new opportunities that will be best realised by the stronger party organisation and more dynamic communications strategies we are now putting in place.
"This new logo - dynamic and vibrant in a way that reflects modern Ireland - encompasses our vision and encapsulates our message as we move forward through the agreement into a new and better Ireland."
The SDLP was confronting new challenges with "imagination and courage," he said.
"We are changing this party without compromising any of our principles."