This chapter examines five main approaches in comparative politics that represent important contributions: old and new institutional analysis, interest approach, ideas approach, individual approach, and the influence of the international environment. The role of ‘interaction’ is also explored. After explaining the use of theory in comparative political analysis, the chapter considers structural functionalism, systems theory, Marxism, corporatism, institutionalism, governance, and comparative political economy. It also discusses behavioural and rational choice approaches, how political culture helps to understand political behaviour in different countries, self-interest in politics, and the implications of globalization for comparative politics. The chapter concludes by assessing the importance of looking at political processes and of defining what the ‘dependent variables’ are.