The study first applies psychological principles of cognitive reasoning to identify typical judicial reasoning errors in sentencing that produce unwarranted sentencing disparity. A review of reasons and purposes in judicial sentencing in Great Britain focuses on the relationship between offense seriousness and prior criminal record and sentencing. This is followed by a discussion of the mathematical measure of proportionality in sentencing (sentencing severity matches offense severity). The variables of culpability, mitigation, and aggravation are reviewed. The book concludes with a discussion of how to address the practical problem of reducing prison overcrowding while maintaining uniform proportionate sentences. Retributive sentencing that uses noncustodial alternatives is considered. 250-item bibliography and subject index.