This book seeks to elucidate its subject-the governing of democratic state-by making intelligible the party politics of democracies. Downs treats this differently than do other students of politics. His explanations are systematically related to, and deducible from, precisely stated assumptions about the motivations that attend the decisions of voters and parties and the environment in which they act. He is consciously concerned with the economy in explanation, that is, with attempting to account for phenomena in terms of a very limited number of facts and postulates. He is concerned also with the central features of party politics in any democratic state, not with that in the United States or any other single country.