How are institutions formed and how do they change? How do institutions interact to produce action? And how formal do institutions need to be to become effective actors of governance? This textbook provides a thorough examination of institutions from a number of theoretical perspectives to identify their key characteristics. Key features of the fourth edition:Eight consistent questions are used to highlight the similarities and differences between institutions, using both formal and informal examplesTwo new chapters focus on informal institutions and the process of institutionalization and deinstitutionalizationA wide range of theories are highlighted, giving students a broad overview of institutional theory in political scienceThe application of these institutional theories is demonstrated using a variety of international examples. For students of comparative politics, political theory and institutions, this textbook will be an essential guide to understanding and analyzing institutions in political science.