This book provides a systematic exploration of party system change. By applying the concept of political entrepreneurship and using a detailed case study of the south Indian state of Tamil Nadu, it demonstrates how party leaders can exercise their agency and drive party system change. Recent developments in Tamil politics are taken into account in the light of the literature on party systems, achieving a classification of the party system and revealing patterns of change. The author explains the process of the change by comparing the careers of successful and failed party leaders, thus identifying the factors that enabled some political entrepreneurs to successfully found political parties and contribute to the process of party system change. Examining issues such as regional parties, political entrepreneurship, social change, caste and religious nationalism, the book illustrates the key forces shaping contemporary Indian politics, and presents an example of how the trend toward identity politics and the rising influence of regional political parties are fashioning a new Indian polity. With a broad cross-disciplinary appeal, the book will be of interest to students of South Asian politics, comparative politics, sociology and anthropology.