We live in an era where someone can contract an infectious disease in Hong Kong, get on a plane, and land in New York City before the incubation period is over. We also live in a time where the wealthiest one percent of people control 34 times more than the wealth of the entire bottom 50 percent of the world's population. Climate change, mass migration, war, and the rise of Artificial Intelligence all pose challenges to maintaining the health of our human species. And yet we march on, beating back illness, disadvantage and suffering, inch by inch. This textbook, now in its third edition, is meant for undergraduate students of health sciences. It offers a grounding in issues in international development and population health. Dr Raywat Deonandan covers epidemiology, economics, history, political science, and many other disciplines as he presents the issues of the day, how we can think about, measure and address them.