This chapter provides a comprehensive review of decision-making theories that seek to account for the behavior of actors, agencies, and institutions. This chapter considers three levels of analysis: (1) systemic-level factors from the lenses of structural realism, liberalism, and constructivism, including human nature, the global system, and state-to-state relations; (2) state-level factors, such as institutional momentum, government agencies, transnational relationships, and policy networks; (3) and individual- and group-level factors, such as political psychology, belief systems, and group influence. Together these factors create a constrained and conflicting environment for policy actors in the U.S. foreign policy process.

At the systemic level, traditional realist theories of power contrast with liberal and critical theories of international relations. Realist theories focus on the inevitability of power clashes and state rivalries, whereas liberal theories tend to emphasize cooperation and institution building. Constructivist and other critical theories emphasize ideas, discourse, economic motives, and interest group involvement in the policy process.

At the state level of foreign policy, governmental institutions and agencies are the main foci of analysis. Differences emerge in the types of policy subgroups that form, such as rigid iron triangles and ad hoc issue networks. Bureaucratic and actor relationships are also important when considering the fragmented and divided political system. At the individual level, belief systems, limits on rationality, and group pressures also constrain and influence the policy process.

At the individual level, presidents and other foreign policymakers take center stage. Here, foreign policy scholars benefit from an interdisciplinary approach, embracing concepts from both political psychology and cognitive psychology. The belief systems and personality types that most influence the decision-making process are highlighted, as well as how these factors change in groupthink and crisis decision-making scenarios.

This chapter provides a necessary segue for the next chapters by discussing policy institutions and actors along with how and why policy decisions are made. Specifically, this chapter emphasizes the connection between domestic and international politics, or two-level game pressures on policy makers. These pressures manifest themselves both inside and outside government, making it difficult to achieve a coherent or unitary foreign policy.