This book brings together in one nicely produced volume a timely, well-written, and comprehensive collection of articles by specialists in the field. The book should be useful for those already working in related areas as well as for newcomers. Where it is particularly helpful is in condensing the vast literature on ubiquitin and putting it into perspective. The easy-to-read style of the best chapters should make the book accessible to new students in the field, and for the more experienced reader it provides a useful source of reference. Many of the chapters are excellent, and the style is mostly clear and concise.