A leadership spill in the Australian Labor Party, the party of opposition in the Parliament of Australia, was held on 27 April 1966. It followed a challenge by party deputy-leader Gough Whitlam against incumbent leader Arthur Calwell. Calwell received 49 votes to Whitlam's 25 in a caucus ballot.[1] After claiming victory Calwell then announced that if Labor was defeated at the impending 1966 federal election, he would not stand for the leadership again.[2]