This book presents an introduction to modern public health seen from the perspective of practitioners of public health medicine. Written for non-practitioners interested in public health and as an essential introduction for those considering a career in public health medicine, the book uses illustrative case studies to demonstrate the practical application of public health techniques. In demonstrating the value of this approach, the book argues for the adoption of a realist health policy and radical reform of clinical medicine - to achieve public health. The skills of public health physicians are central to planning health services, purchasing effective and cost-effective treatments, and improving the quality of services. It is vital that those who plan and deliver health care understand their work and appreciate their contribution. This book describes that contribution, and provides a powerful analysis of the challenges the NHS and the wider community face in improving health.