It is appropriate to begin our discussion of theories of international regimes with those contributions which can be referred to as interest-based or neoliberal. This school of thought has come to represent the mainstream approach to analyzing international regimes, and the other two schools, realism and cognitivism, regularly make reference to its arguments in order to give their own positions a clear profile. This is not to say that the neoliberal account of regimes owes nothing to the ideas that are fundamental to power- and knowledge-based theories. Realism in particular provides central assumptions which leading interest-based theories of regimes such as Keohane's “contractualism” and those contributions which we call “situation-structural” have consciously adopted. Before turning to individual interest-based theories, we therefore highlight major commonalities and differences between realism and neoliberalism.

A most important point of agreement between realist and neoliberal theories of international regimes is their shared commitment to rationalism, a meta-theoretical tenet which portrays states as self-interested, goal-seeking actors whose behavior can be accounted for in terms of the maximization of individual utility (where the relevant individuals are states). Foreign policies as well as international institutions are to be reconstructed as outcomes of calculations of advantage made by states.