This chapter examines the role of institutions and how institutionalism is applied in the analysis of politics in the developing world. It begins with a discussion of three main strands of institutionalism: sociological institutionalism, rational choice institutionalism, and historical institutionalism. It then considers political institutions in developing countries as well as the interrelationship between formal and informal institutions. Three cases are presented: the case from sub-Saharan Africa illustrates the salience of neo-patrimonial politics and competing informal and formal institutions, the second case relates to campaign clientelism in Peru and the third is concerned with electoral quotas in India. The chapter concludes by addressing the question of the extent to which the new institutionalism is an appropriate tool of analysis for developing countries.