India is a large, heterogeneous and complex nation, with multiple languages, religions and ethnicities, and over one billion people. It stands out in having held together while sustaining a working democracy for over five decades, at relatively low levels of income. One of the main institutional aspects of managing heterogeneity to preserve national unity is the structures of Indian federalism. This paper traces some of the features of Indian federal institutions, focusing on their contribution to this 'holding together.' It reviews the conceptual and analytical underpinnings of the role of federal structures in sustaining unity, and summarizes historical developments and current institutional structures of the Indian case. It assesses the role of federal dimensions of political, administrative and judicial structures in the holding together function. It also examines fiscal federal institutions and their impacts, including distributional and growth issues. It also separately focuses specifically on the special treatment of what may be characterized as India's periphery.JEL codes: P26, P35, H1, H7