A concise yet penetrating analysis of how modern American presidents have--and have not--incorporated ethics into their foreign policy. Americans constantly make moral judgments about presidents and foreign policy. Unfortunately, many of these assessments are poorly thought through. In Do Morals Matter?, Joseph S. Nye, Jr. provides a concise yet penetrating analysis of the role of ethics in US foreign policy since Franklin Delano Roosevelt's presidency onward. Nye works through each presidency from FDR to Trump and scores their foreign policy on three ethical dimensions: their intentions, the means they used, and the consequences of their decisions. He also evaluates their leadership qualities, elaborating on which approaches work and which ones do not. Regardless of a president's policy preference, Nye shows that each one was not fully constrained by the structure of the system and actually had choices. Since we so often apply moral reasoning to foreign policy, Nye suggests how to do it better. Most importantly, he shows that presidents need to factor in both the political context and the availability of resources when deciding how to implement an ethical policy-especially in a future international system that presents not only great power competition from China and Russia, but a host of additional transnational threats.