This article argues that Hayek's Road to Serfdom should be read in the light of his contemporaneous studies in the history of European social and political thought, and traces the affinities between his and Halévy's work on the history of socialism. Both saw Saint-Simonism rather than Marxism as embodying the essence of socialism, and both saw the cult of 'organization', rather than the idea of class conflict, as its most characteristic feature. It is tentatively suggested that Halévy's writings exercised a significant influence on the formulation of Hayek's most famous work.key words: Halévy, Hayek, history of ideas, Saint-Simon