Abstract: This article assesses the relative economic costs and benefits of alternative sentences. A conceptual economic model is developed in which the benefits are the rehabilitation, incapacitation, deterrence and retribution effects of prison. A review of the literature was undertaken to identify economic studies that measure these effects. The evidence available tends to focus on costs and the rehabilitation and incapacitation effects. The evidence on the deterrence effect takes two forms – theoretical models and empirical analysis. Little economic evidence on the retribution effect of prison was identified. In conclusion, whatever the other reasons put forward for or against the use of prison, it is reasonable to conclude that using it for anyone but those convicted of serious offences is a waste of public resources.