Although comparative politics is conventionally seen as the study of politics across countries, the field has a longstanding and increasingly prominent tradition in national contexts; focusing on subnational units, institutions, actors and processes. This book offers the first comprehensive assessment of the substantive, theoretical, and methodological contributions. With empirical chapters from across the contemporary Global South, including India, Mexico, and China, as well as Russia, the contributors show how subnational research provides useful insights about substantive themes in political science, from regimes and representation, to states and security, to social and economic development. In addition to methodological chapters with specific guidance about best practices for doing subnational research, this volume also proposes a set of strategies for subnational research, assesses their strengths and weaknesses, and offers illustrative empirical applications.