Over the past five years, legislative studies have emerged as a field of inquiry in political science. Many political science associations, both national and international, have created standing sections on legislative studies. There has also been a proliferation of literature on legislatures and legislators. This book focuses on legislatures and how they matter, how they have adapted to changes such as globalization and judicialization, and how they have survived the transition to mass democracies. It examines the reasons why legislatures still exist despite accusations of anachronism, decline, irrelevance, and dysfunctionality, and how they have survived even when political parties suffer from a declining support base. The book also considers theoretical approaches in legislative studies, such as rational choice theory and the sociological approach, along with the role of debate and deliberation in legislatures, the major challenges of legislative interviews and legislative surveys, candidate selection and its implications for legislative politics, and the relationship between electoral systems and legislative behavior. Furthermore, it discusses the impact of legislative careers on legislative capacity, the internal organizational structure, and rules of legislative organization, bicameralism, and legislative committees, legislative agenda-setting and lawmaking, the how and why of political parties as well as coalitions of parties, and effects of legislatures on public finance.