This is a history of political ideologies during the period famously described by Eric Hobsbawn as 'The Age of Extremes' - from the First World War to the collapse of the Soviet Union. Ideologies in the Age of Extremes introduces the key ideologies of the age; liberalism, conservatism, communism and fascism. Willie Thompson identifies the political influence of mass movements as a key feature. He uses a powerful approach that considers the different ideologies in relation to each other. This allows him to shows that they often emerged from a common root or merged into a common future, stealing each other's clothes and reinventing themselves as the stark opposite of a competing ideology. This sophisticated yet accessible analysis will be of great interest to students of 20th century history and political theory.