In this brief, readable, and revealing book, one of the pioneers of the now rapidly evolving field of DNA repair traces the history of the discovery of the more important mechanisms by which cells respond to DNA damage. Errol Friedberg has written an enjoyable and informative introduction to the study of DNA mutagenesis and re-pair that will interest students at an advanced undergraduate or graduate student level as well as investigators in fields as diverse as oncogenesis, cell cycle regulation, transcription and DNA replication.