Since the World Health Organization (WHO) was founded in 1948, the world has changed dramatically and so too has its health. But while some scourges (e.g. smallpox and polio) have subsided, others have made a comeback (e.g. tuberculosis) and frightening new diseases (e.g. Ebola and Marburg) have appeared. This book is primarily for young people, especially those interested in working in public health. It explains in simple, non-technical language how humankind developed techniques to protect the health of communities, drawing on first-hand interviews with leading public health figures. It covers a wide range of topics, from the control of infectious disease outbreaks to fighting the stigma attached to mental health conditions. These narratives, told from many parts of the world, show how individuals, communities, institutions and countries can improve people's health when they work together. They show the role that WHO has played in providing countries with the technical support and coordination to make progress in health possible.