He became involved in the civil rights movement during the 1960s and was elected to Stormont in 1969. He co-founded the Social Democratic and Labour Party (SDLP) in 1970 and was its leader from 1979 to 2001.
He played a major role in the peace process, from the Anglo-Irish Agreement in 1985 to the Good Friday Agreement in 1998. He was awarded the Nobel Peace Prize in 1998 and was named 'Ireland’s Greatest' in a public poll by RTÉ in 2010. Pope Benedict made him a Knight of St Gregory in 2012.