The 1951 referendum campaign to ban communism produced a massive shift of public opinion, from Yes to No. This article attempts to explain why. It examines the political appeals and rhetoric of the Liberal and Labor Party leaders, their coverage across the entire metropolitan press, and their use of radio. Breaking with earlier interpretations, it argues that Evatt's campaign encompassed wider issues than civil liberties, suggests that Menzies' campaign was damaged by unruly meetings and shows that neither side appealed exclusively to reason or to passion. Ultimately, the success of the No campaign rested on its capacity to mobilise most Labor voters and to attract some Liberals. This was an extraordinary achievement, but it was secured using routine forms of electioneering.