This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book provides an overview of the framework of actor-centered institutionalism. It proposes to explain policy choices by focusing on the interactions among individual, collective, and corporate actors that are shaped by the institutional settings within which they take place. The book discusses categories for describing the action resources and the action orientations of such actors. It describes the relationship in which the actors involved in policy interactions find themselves vis-à-vis one another with regard to their strategy options and with regard to their outcome preferences. The book deals with "unilateral action" under the structural conditions of "anarchic fields" or "minimal institutions." It also discusses "negotiated agreements" under the structural conditions of minimal institutions, networks, regimes, and "joint-decision systems." The book focuses on binding decisions imposed by hierarchical direction within organizations and within the state.