Book excerpt: N-of-1 trials, a type of individualized randomized controlled trial, are relevant to almost every discipline in medicine and psychology. They can tell the clinician with precision whether a treatment works in that individual, which distinguishes from the information available from most other trial designs. They have the potential to revolutionize the way clinical medicine is practiced. Whether you are a busy clinician, a researcher or a student, this book provides everything you need to know about N-of-1 trials. Written and edited by some of the world’s leading experts on N-of-1 trials, the book presents state of the art knowledge about N-of-1 trials, with chapters on ethics, statistics, health economics, design, analysis and reporting, and more. Full of examples and well illustrated, it is a comprehensive compendium of issues surrounding the design, conduct, interpretation and implementation of N-of-1 trials in a health system.