The article seeks to assess critically the theory of rational choice, especially with regard to its applicability in the field of comparative politics. Rather than focus on the epistemological preconditions of rational choice, this article pin-points ways in which this theory can be actually used as a research tool to address central issues in comparative political research. The first part of the article lays out the fundamental components of rational choice theory, with particular emphasis on actors, preferences, and strategies; surveys its major strengths and weaknesses; addresses the question of the compatibility between modelling abstraction and empirical validation; deals with the issue of irrational behaviour; points to factors which constrain individual behaviour and rationality, particularly institutions; and compares rational choice to other approaches. The second part of the article introduces a methodological framework based on the assumptions and logic of rational choice, adapted to the requirements and needs of comparative politics. The section’s core argument is that under certain conditions, rational choice is an analytical tool particularly suited to the method, practice, and object of comparative politics. Moreover, it allows the re-introduction in political science of two critical and neglected dimensions: the historical and narrative dimensions. The formation of confessional parties in Europe at the end of the nineteenth and the beginning of the twentieth century is used as a case study. The interaction between the key political actors, the church and conservative parties, is modeled and empirical predictions are derived. The application of rational choice to the question of party formation produces an account of the formation of confessional parties which is superior to and more parsimonious than existing accounts.