Rational choice (also termed rationalism) is a prominent framework in international relations scholarship. Rational choice is not a substantive theory of international politics, but rather a methodological approach that focuses on certain types of social explanation for phenomena. In that sense, it is similar to constructivism, and differs from liberalism and realism, which are substantive theories of world politics. Rationalist analyses have been used to substantiate realist theories, as well as liberal theories of international relations.

Rational choice research tends to explain conditions that bring about outcomes or patterns of behavior if relevant actors behave rationally. Key concepts in rational choice research in international relations include incomplete information, credibility, signaling, transaction costs, trust, and audience costs.

According to James D. Fearon, a rational choice research project typically proceeds in the following fashion:

Actors do not have to be fully rational. There are varieties of rationality (e.g. thick and thin rationality). Rational choice scholarship may emphasize materialist variables, but rational choice and materialism are not necessarily synonymous.

Rational choice explanations for conflict and the lack of cooperation in international politics frequently point to factors such as incomplete information, and a lack of credibility. Chances of cooperation and peaceful resolution can be increased through costly signaling, long shadows of the future, and tit-for-tat bargaining strategies. According to rationalist analyses, institutions may facilitate cooperation by increasing information, reducing transaction costs, and reducing collective action problems.

Rational choice analyses tend to conceptualize norms as adhering to a "logic of consequence" rather than the constructivist “logic of appropriateness”. The “logic of consequences” entails that actors are assumed to choose the most efficient means to reach their goals on the basis of a cost-benefit analysis. This stands in contrast to the logic of appropriateness whereby actors follow “internalized prescriptions of what is socially defined as normal, true, right, or good, without, or in spite of calculation of consequences and expected utility”. Jeffrey Checkel writes that there are two common types of explanations for the efficacy of norms:

According to Duncan Snidal, the advantages of rational choice research is that the formalization of arguments helps to clarify the underlying logic of authors' claims, the clarity of arguments makes rational choice arguments falsifiable, and rational choice arguments lend themselves to empirical validation through case studies.

Constructivist scholars argue that while rational choice approaches may be useful to explain the interactions of actors with given interests, rationalist approaches are ultimately limited in explaining how those interests emerged in the first place. In other words, rationalists use exogenously given interests, but struggle to account for endogenously given interests. According to Duncan Snidal, rationalists are good at explaining continuity and stability (equilibrium solutions), but are less adept at explaining why change occurs. He also argues that rationalists are ill-equipped to incorporate norms in their models. According to Sidney Verba, a rational choice model of international relations depends on the quality of assumptions in the model; bad assumptions undercut the usefulness and adequacy of the model.