Unlike in many other sentencing reforms, guidelines have generally been developed out of an empirical analysis of past sentencing decisions through the identification of variables most predictive of sentence. However, when the statistical analysis is inadequate or faulty, the resultant sentencing guidelines must be questioned. Presented is a reanalysis of the original data used to develop Cook County's sentencing guidelines. Generally, the current sentencing guidelines used in Cook County are not found to be predictive of sentence. Implications of this finding are discussed. (Author abstract)