The class nature and political trajectory of the British Labour Party (BLP) and the Australian Labor Party (ALP) have been remarkably similar. The greatest manifestations of this similarity have been in terms of each party being the main representative working class political party; the structural significance of trade unions within both parties; and each party being characterised by a dominant ideology of ‘labourism’. However, there have also been significant differences. The ALP succeeded in consolidating as an electoral force much earlier, and has enjoyed somewhat more electoral success ever since. Furthermore, the programmatic expression of labourism differed in some important respects. This article first aims to explain the early electoral success of the ALP through the consideration of four factors: the timing of political consolidation, the structure of the Australian and British states, the political environment, class structure and party membership. Secondly, it examines the trajectories of the BLP and ALP in the late nineteenth and twentieth centuries through the prism of labourism, which has itself been affected by changes in class structure and party membership.