Depression and physical illness are intimately related. Depressed mood is thought to contribute to the development and progression of some illnesses, while physical illness can in turn increase the risk of depression. This book provides a critical overview of the evidence linking depression with several major health conditions, including coronary heart disease, diabetes, cancer, chronic pain, disability, chronic fatigue and obesity. It also explores the biological and behavioral processes underlying the association, discussing the role of neuroendocrine, immunological and inflammatory pathways, and the relationship between depression and health behaviours such as smoking, physical activity and adherence to medical advice. It combines a thorough analysis of the clinical, biological and epidemiological data with guidance to health professionals and patients on how to manage depression in people suffering from physical illness, pointing the way to an integrated approach to health care.