While different versions of democratic theory often deal with political institutions like parliaments and elections in broad terms (see Chapter 1), none can avoid giving at least some attention to such institutions. As groups of people begin to make decisions about some aspect of their lives, they inevitably will begin to develop more or less formal rules about how those decisions are made, how they can be changed, and so on. Democratic intentions can be thwarted by these rules and values. The institutionalists discussed in this chapter pay systematic attention to the ways in which different institutional rules, procedures and cultures affect the processes and outcomes of political and policy decisions. As with democratic theories, there is a range of institutional approaches to politics and policy-making – the ‘old institutionalism’, as well as the normative, rational choice, historical, empirical, network, sociological, constructivist and feminist variations of ‘new institutionalism’. This chapter assesses the strengths and limitations of these various varieties of institutionalism.