Former Alliance and independent councillor Brian Wilson joined the Greens. He was elected in North Down in a significant breakthrough for the party.
The seat was retained by the party in the 2011 assembly elections by Steven Agnew.
Breaking the hold of traditional unionist and nationalist parties in Northern Ireland has been a challenge for non-aligned groups for many years.
In the 2009 European election, the Green Party in Northern Ireland took more than 3% of the vote with Mr Agnew as a candidate, polling 15,764 votes.
This was more than three times the Green Party's previous poll result. However, in the 2014 European election the Green vote fell to 10,598.
It is the only Northern Ireland party that does not accept corporate donations.
The Green Party in Northern Ireland works in co-operation with other Greens across the European Union, and has a close relationship with its counterpart in the Republic of Ireland.
The party has four councillors.
The Green Party in Northern Ireland first gained a foothold in the Northern Ireland Assembly in 2007.