The purpose of this thesis is to explore the differences that emerged among the social-democratic 'right' wing of the British Labour Party in the 1970s and early 1980s. For most of the early post-war period, the Labour right was a cohesive unit, with a shared commitment towards gradual, pragmatic reform and welfare-state capitalism. However, even then there was an awareness that within its ranks there were two diverging tendencies. The first tendency, known as 'revisionism', was the intellectual basis for British social-democracy from the 1940s onwards, and was associated with the group of educated, middle-class politicians who supported Hugh Gaitskell during his days as leader of the party. The second tendency, often known as the 'traditionalist' or 'Labourist' right, was more nebulous and therefore harder to define, as it rarely dissented from revisionism in terms of doctrine or policy; but it was widely agreed to be much more 'working-class' in its composition, was considered by its critics to be conservative rather than progressive in instinct, and was usually conflated with trade union politics. By the 1970s, the alliance between them was deemed to be under severe strain. But in trying to explain how that came about, this thesis seeks to determine whether or not the dichotomy between revisionism and traditionalism was actually as relevant in sowing discord as it sometimes appeared to be. In the first chapter of my thesis I examine these two tendencies in greater detail, and consider the potential for further division within the right that was caused by differing interpretations of three important social-democratic ethics - namely, egalitarianism, libertarianism, and rationalism. The second chapter concerns the debates surrounding Britain's application to join the European Economic Community (EEC) in 1971, which - by splitting the Labour right into opposing 'pro' and 'anti' camps - has often been viewed as a proxy for the tensions that existed between the revisionists and the traditionalists. The third chapter scrutinises attempts from within the right to reform industrial relations, focusing mainly on incomes policy and 'workers participation', and the consequences this had for the Labourist tendency. Chapter four analyses the gradual rift that developed between two leading revisionists, Anthony Crosland and Roy Jenkins, and the emergence among the latter's supporters of a new, liberal form of 'post-revisionism'. The fifth chapter discusses the impact of a more explicitly 'populist' approach that was developed by certain right-wing activists on the party's fringes, and the consequences this had for the revisionist/traditionalist divide. And lastly, chapter six examines the creation of the breakaway Social Democratic Party (SDP) in 1981, and the efforts of its leaders to eradicate any traces of their Labour Party past by emphasising novelty and modernity to their new support base instead.