Vast global resources are ploughed into the delivery of treatment interventions ranging from diet and lifestyle advice through to complex surgery. In all cases, whatever the intervention, unless the recipient is engaged with the process and understands why the intervention has been offered and the part they play in its success, compliance will be an issue. Even where the individual does engage and understand, he or she may choose, in the light of that knowledge, not to comply. This book aims to explore the key factors which drive compliance and the part that healthcare professionals can play in improving this, with the key underlying goal of improving public health in its broadest sense. During clinical trials, non-compliance undermines the accuracy of the data generated from the whole trial as well as particular aspects such as the efficacy of different dosages. In more general treatment of patients, improving compliance improves the real world effectiveness of treatments, which benefits healthcare providers and the pharmaceutical industry alike. Western medicine faces a number of key challenges, not least: an aging population requiring increasing levels of treatment and prescription, spiralling costs of technology and treatment, and growing levels of viral resistance to drugs. Non-compliance is estimated to cost the pharma industry US$70 billion per year. No figures exist for the cost to healthcare insurers and public health but non-compliance is undoubtedly one of the top five issues facing both drug developers and healthcare providers.