This book examines the evidence for the effectiveness of prison and programmes in the community aimed at reducing reoffending and some of the claims and counter-claims for whether “prison works”. The main focus of this book is the high prison population and austere financial climate in England and Wales, the challenges these present for the National Offender Management Service (NOMS) and particularly HM Prison Service, and the emerging evidence of “what works” in reducing reoffending. Chapter 1 - For decades, one of the preoccupations of criminologists, politicians and commentators has been whether, as it has been claimed, “prison works”. This paper therefore examines the evidence for the effectiveness of prison and programmes in the community aimed at reducing reoffending and some of the claims and counter-claims for whether “prison works”. The main focus of this paper is the high prison population and austere financial climate in England and Wales, the challenges these present for the National Offender Management Service (NOMS) and particularly HM Prison Service, and the emerging evidence of “what works” in reducing reoffending. Some of the research, though, has been conducted outside the UK and so some of the evidence cited is international. The purposes of imprisonment are often cited as incapacitation, punishment, retribution, deterrence and rehabilitation, but views differ as to the relative importance and priority of each. There is a broad consensus that, for the most serious offences, a custodial sentence is likely to be the most appropriate one. Prison also offers the public some respite, by taking offenders off the streets and so, in that sense, “prison works”. That much is fairly widely agreed.