This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book addresses the main lines of reasoning of the new political institutionalism and rational choice theory. It discusses the notion of political choice, deals with possible syntheses of concepts of rational choice and action with the idea of institutional embeddedness, constraints, and opportunities of policy-making processes. Political choices aim at desired macro states and imply actors' aspirations to guide social processes through collective action or individual interaction. Political choices attempt to overcome self-regulatory social processes. Political choice, shaping mandatory policies for collectivities, is concerned with the provision of public goods. The book focuses on the relationship between political institution, on the one hand, and the quality of policy choice, on the other. It shows how administrative rules determine administrative action, and thus, substitute for consequential rational choices in politics and administration.