The motivation for writing this book was a request from managers, policy makers and students for a textbook on the systems approach in public health and epidemiology. If you type the keywords "public health" and "systems approach" into a search engine, you will find a number of works that have those terms in their titles. Looking through their text, you then struggle to find even the slightest mention of what the systems approach means, much less how to apply it to problem solving. To put it another way, there was nothing to recommend it to Masters and PhD students, management clients and politicians making decisions about public affairs, and so the book that has just been published by Cambridge Scholars Publishing in the UK was born.