Southeast Asian historians have represented the Pacific War (1942–1945) in terms of either change or continuity. First, this chapter discusses the Pacific War in Southeast Asia from the point of view of public health by focusing on change. During the war, the Japanese used public health as an instrument of political mobilization and repeatedly stressed the importance of spirituality and discipline in ensuring their victory. Speaking of Masjarakat Baroe (New Society), Indonesian physicians expressed their role in cultivating national vitality. But the chapter also acknowledges a certain continuity between prewar and postwar international health. For instance, following the Japanese surrender (1945), Dutch doctors could no longer lay claims to rural hygiene in Java; it belonged to 1930s Rockefeller-trained Indonesian physicians. Second, this chapter describes the wartime discovery of the insecticide DDT and how it ushered in the possibility of disease eradication. Third, the chapter traces the historical circumstances that led to the emergence of health as a “right” in the aftermath of the Pacific War. Furthermore, I examine the shift in international health from interwar networks of loosely affiliated experts to a postwar set of connections based on the assumption that states were responsible for guaranteeing population health.