Epidemiology is the science that underpins health and health care, and is concerned with the pattern, frequency and causes of disease. This introductory text describes and illustrates epidemiology and its applications to policy making, health service planning, and health promotion. Raj Bhopal developed a conceptual approach to epidemiology in the first edition of this successful text, which involved a systematic focus on underlying concepts and fundamental principles, and this second edition expands upon this popular method. It emphasizes theories and principles, as the bedrock of methodology, countering the mounting criticism that epidemiology is an atheoretical discipline. The interdependence of epidemiological studies and their essential unit within a theoretical, technical and ethical framework is an important theme of this book. The emphasis is on interactive learning throughout, with each chapter including learning objectives, both theoretical and numerical exercises, recent examination questions from relevant courses, and a summary. The text is richly illustrated, with detailed material summarised in tables. The book is written in plain language, with all the necessary technical and specialised terminology explained and defined in a glossary.