Why are some communities healthier than others-and why do health inequalities persist even in wealthy societies? In this timely and accessible second edition, epidemiologist and educator Raywat Deonandan explores the forces that shape health far beyond biology and medical care. From income, education, gender, disability, and social support to Indigenous health, climate change, digital technologies, and health systems, this book examines the complex social, economic, political, and environmental conditions that influence who becomes sick, who stays well, and who gets left behind. Written for students, educators, and curious readers alike, Determinants of Health, 2nd Edition combines clear explanations with contemporary data, global examples, and a strong Canadian perspective. Readers are introduced to the core concepts of population health while being challenged to think critically about fairness, policy, prevention, and the real-world roots of disease. New to this edition are updated statistics, modernized terminology, expanded discussion of digital determinants of health, dedicated chapters on climate change and health systems, and refreshed examples reflecting today's rapidly changing world. Ideal for undergraduate courses in health sciences, public health, nursing, social work, and policy studies, this book is both an introduction and an invitation: to see health not merely as a medical outcome, but as a reflection of how societies are organized. Understanding health means understanding the world.