In many legal systems around the world the doctrine of good faith is recognized as one of the general principles of contract law. Good faith is an elusive idea, taking on different meanings from one context to another. Accordingly, this text examines matters of concept and context. The book tackles the central conceptual question of what is meant by a doctrine of good faith, considers the fundamental question of how good faith controls on the consumer contract terms are to be justified, and presents a view of the development of good faith in the United States and South Africa. The book also presents opposing views on the sense of adopting a good faith principle.