The Progressive Democrats are planning a major recruitment drive next year in an effort to sustain the party's future after 20 years in existence.
The party was founded during Christmas week in 1985 by Mr Dessie O'Malley after he split from Fianna Fáil. It has since served in power for over half of its existence.
Current and former parliamentary members and party staff gathered in their Dublin HQ today to celebrate the anniversary of the party's foundation.
They pledged to hold a series of regional public meetings, conduct a membership drive and distribute information in key constituencies.
Party president Mr Michael McDowell today promised "political mapping and vision to drive the political agenda just as radically as we drove the political agenda for the last 20 years".
He added: "We will be the driving force in bringing about increased success for this country over the next 20 years."
The Tánaiste and PD leader Ms Harney said the PDs helped to transform the country through its policy agenda. "I don't think anybody can take that away from us." She said the party's early economic policies were opposed by the main parties and described as "crazy" by then Taoiseach, Mr Garret FitzGerald.
"In Ireland, if you espouse low taxation and pro-enterprise, people assume that you're fundamentalist or right-wing. Nothing annoys me more than to be described as right-wing."
Ms Harney said the party was founded in an Ireland where unemployment was at 17 per cent, the standard tax rate was 35 per cent and divorce and homosexuality were illegal. "People described our policies as a form of Utopia. There were very few people in Ireland that predicted that we would still be around now."
Mr O'Malley remarked that Ireland had become one of the most successful countries in the EU from being described as the 'sick man of Europe.'
"The International Monetary Fund was waiting to move into Ireland to tell us how to manage our affairs," he said. Mr O'Malley who is now a director with the European Bank for Reconstruction and Development in London, said the PDs helped to socially transform the State from a "homogenous and inward-looking society."
A book is being compiled about the party to celebrate its first two decades.