David Ford has led the cross-community Alliance party since 2001.
He took on the leadership after Sean Neeson resigned in the face of poor election results.
Mr Ford, a former social worker, has been Northern Ireland's justice minister since April 2010 - the first local minister in that role in nearly 40 years.
Mr Ford has represented South Antrim as an MLA since 1998. He was also a member of Antrim Borough Council.
Born in Kent, with a Welsh father and mother from Northern Ireland, he grew up in England, but spent summer holidays on his uncle's farm in Gortin, County Tyrone.
He moved to Northern Ireland permanently in 1969 and studied economics at Queen's University in Belfast.
He joined Alliance at university and spent a year as a volunteer at the ecumenical centre, Corrymeela.
Mr Ford's entry into full-time politics was in 1990 when he became Alliance's general secretary.
He has campaigned for a better railway network and has a strong interest in agricultural and environmental affairs.
When the then Ulster Unionist leader David Trimble lost his assembly majority in 2001, Mr Ford redesignated as a unionist with two colleagues for 22 minutes.
It helped pave the way for Mr Trimble get re-elected as first minister of Northern Ireland.
At the time, Mr Ford, a father-of-four said he would never again allow himself to be what he described as the "back-end of a pantomime horse".
- Promote integration and a shared future - division costs over £1bn pa
- Build a 21st century economy that can compete globally
- Invest in public services, like schools and hospitals
- Reboot NI political system: ensure openness about donations; create an opposition; push to lower voting age to 16
Mr Ford's department recently ran a public consultation on proposals to change Northern Ireland's abortion law, which differs from the rest of the UK.
His department recommended allowing abortion in lethal foetal abnormality cases but did not make recommendations for rape cases.
His party also voted to endorse gay marriage in 2012.
Amid the ensuing controversy, Mr Ford stepped aside temporarily as an elder at his Presbyterian church in County Antrim.
Mr Ford is not standing in the 2015 general election.