Chapter 2 draws insights from FPA to explain the relationships among power, beliefs and interests as causes of distinctive American IL policy. The focus is on ‘foreign policy ideology’ as the ideational concept that best captures the transformation of power into ideas capable of shaping global interests. A generation of empirical survey research, combined with a rich history of diplomatic thought, has shown American foreign policy ideology to be structured by two dimensions forming an influential four-part typology. A ‘governance’ dimension measures whether American power is exercised primarily through international institutions dominated by elites, or conversely whether US foreign policy interests are advanced through domestic law and institutions under popular control. A second ‘values’ dimension measures whether US policy promotes values of individual liberty through law, or whether it is used to promote illiberal national security or non-universal cultural and identity values. IL policy can thus be located between ‘internationalist–nationalist’ positions on the governance dimension and ‘liberal–illiberal’ positions on the cross-cutting values dimension, which together form four ideal policy types: ‘liberal internationalism’, ‘illiberal internationalism’, ‘liberal nationalism’ and ‘illiberal nationalism’.