This lecture searches for solutions to the most perplexing problems in global health—problems so important that they affect the fate of millions of people, with economic, political, and security ramifications for the world’s population. No State, acting alone, can insulate itself from major health hazards. The determinants of health (e.g., pathogens, air, food, water, even lifestyle choices) do not originate solely within national borders. Health threats inexorably spread to neighboring countries, regions, and even continents. It is for this reason that safeguarding the world’s population requires cooperation and global governance.