This is the first book to provide a comprehensive overview of the social and technological context from which eHealth applications have arisen, the psychological principles on which they are based, and the key development and evaluation issues relevant to their successful intervention. Integrating how eHealth applications can be used for both mental and physical health issues, it presents a complete guide to what eHealth means in theory, as well as how it can be used in practice. Inspired by the principles and structure of the CeHRes Roadmap, a multidisciplinary framework that combines and uses aspects from approaches such as human-centred design, persuasive technology and business modelling, the book first examines the theoretical foundations of eHealth and then assesses its practical application and assessment. Including case studies, a glossary of key terms, and end of chapter summaries, this ground-breaking book provides a holistic overview of one of the most important recent developments in healthcare. It will be essential reading for students, researchers and professionals across the fields of health psychology, public health and design technology.