The Conservative Party was in government for almost all of the decade after the First World War, during which it faced not only economic problems but also the political threat of the advance of the Labour Party. Socialism raised the challenge of a greatly extended role for the state, and in response to this and to tackle the difficulties of industry and the high level of unemployment, which Conservatives attributed to the free trade economy, the party returned in 1923 and 1930–2 to its pre-war advocacy of a system of tariff protection linked to imperial preference. These factors have previously been viewed from separate perspectives, and accounts of the development of the British state have treated Conservative attitudes as simply negative. This article explores the more varied strands of Conservative opinion about the role of the state in the inter-war period, and links these to the party's governing practice in key aspects of economic policy in the decade after 1918, and its attempts to introduce protective tariffs in 1923 and 1930–2. It is based upon contemporary discussions of Conservative principles and policies by active politicians and propagandists, and upon the private correspondence of the party's parliamentary leadership.