A number of writers working in the fields of history and industrial relations have claimed a correlation between long-wave economics and the changing fortunes of political and social movements of the left and right. They have suggested both particular patterns of development and causations but often on the basis of piecemeal evidence, lacking a comprehensive theoretical and empirical basis. This thesis tests the validity of such a correlation through a comparative historical analysis of the domestic political histories of Britain, France, Germany and the USA over the four long-waves that have occurred in modern times; those of 1803-1848, 1848-1896, 1896-1948 and 1948-1998. It finds, that since industrialization, there has been a distinct and repeating pattern of political and social development that can be correlated with long-wave economics. Common ground is found with existing theoretical patterns, though also notable areas of difference, and this thesis provides a more comprehensive pattern of development. The thesis proceeds to explore possible causations for the pattern found. It does so by using existing political science theories explaining political change; those concerning voting behaviour, class struggle and party competition. It finds that aspects of these theories can be used to explain the pattern of development found. Above all, populations experiencing the different economic phases of the long-wave undergo significant motivational changes that are reflected in the shifting fortunes of the left and right. The thesis concludes by analyzing these findings and highlighting advances made on existing accounts. It also discusses those events within modern history that could be regarded as anomalous, with the intention of further understanding this process. Finally, it discusses the implications of the findings of this thesis for long-wave and political science theory.