Complexity theory is a collection of concepts ideas and perspectives developed largely in fields outside medicine. It allows us to study health care delivery using the metaphor of an ecosystem rather than a machine. This timely book explores the ways complexity theory may assist in the provision of clinical healthcare. It explains the foundations of the theory behind complexity its place in clinical medicine and in the wider scientific context using examples of its application in current and potential future medical scenarios. Drawing on insights from diverse areas including ecology evolutionary theory and computer science itit demonstrates the relevance of complexity to cardiology diabetes and mental health to consultation dynamics and decision support and to the delivery of other aspects of care through more informed use of health informatics. The increasingly complex arena of clinical medicine requires new models on which to manage uncertainty recognise and value diversity and process information. All clinicians and managers in primary and secondary care will find this book useful and engaging reading. ''The fashionable drive for a narrowly defined evidence-based practice is likely to accelerate trends which many of us fear: a retreat from clinical intuition to defensive documentation; from acumen to investigation; from values-based policy to techno-managerialism. The ideas addressed in this book written by those who are pioneering the application of complexity theory to clinical practice appear to provide a science-based and rigorous defence against the simplistic thinking which has impelled such dangerous trends. This is an important book it is timely and it is to be welcomed'' Marshall Marinker in the Foreword