Over the past twenty years, relevance theory has become a key area of study within semantics and pragmatics. In this comprehensive new textbook, Billy Clark introduces the key elements of the theory and how they interconnect. The book is divided into two parts - the first providing an overview of the essential machinery of the theory, and the second exploring how the original theory has been extended, applied and critically discussed. Clark offers a systematic framework for understanding the theory from the basics up, building a complete picture and providing the basis for advanced research across a range of topics. With this book, students will understand the fundamentals of relevance theory, its origins in the work of Grice, the relationship it has to other approaches, and its place within recent developments and debates.