The 1959 Australian and New Zealand International Congress for Peace and Disarmament, held in Melbourne, was the first major public event for the left in Australia after the splits in the ALP and the CPA that had occurred between 1955 and 1958. It was notable not so much for its success in attracting large numbers of delegates and for the declarations that came from it as for the brawling that took place during it, particularly over the issue of freedom of speech and the gaoling or execution of dissidents in the Soviet Union and Hungary. The Congress for Cultural Freedom and its allies had prior to the Congress organised groups to support the dissidents, but the members of these groups were seen by the Congress organisers as right-wing disrupters trying to destroy the unity of the Congress and to divert it from its primary objective. Although the organisers secured the numbers on the floor of the Congress and at its constituent special interest meetings, the conflict revealed new divisions on the left, between former Communists and younger members of a new left on the one hand, and the continuing leadership of the CPA and of the Victorian ALP on the other. This paper challenges the view that the Congress achieved a unity on the left in support of its aims. It shows how new alliances cut across old divisions between a left aligned with the Communist party and a right aligned with Catholic Action. The new divisions helped to paralyse Labor as a political force for another decade.