Book excerpt: Perhaps no other public policy issue has greater potential to affect some of the most significant economic, political, social, and ethical changes of the 21st century than global health. In this book, a scholar/physician team authors a comprehensive introduction to global health issues and emphasises the potential of public health intervention to improve the longevity and quality of human life across the globe. The authors have lived and worked in Africa as well as in medically underserved areas of the United States, so they write with firsthand experience and authority. Using themes of interconnectedness, globalisation, and united concern from citizens, this book encourages readers to consider the role that they might play as engaged citizens in taking on the global public health challenges of the 21st century including everything from AIDs and flu to tobacco, obesity, and threats in conflict zones.