The study was conducted between March 1991 and May 1992 in accordance with generally accepted government auditing standards. All of the sentencing data used in the analyses were provided by the Sentencing Commission. The study concludes that at this time neither the GAO nor the Sentencing Commission can definitively answer the central question posed by Congress, that is, whether the sentencing guidelines have been effective in reducing sentencing disparity. Where there were sufficient data for analysis of comparable preguidelines and guidelines cases, the GAO finding concurred with those of the Commission, namely, that the amount of sentencing disparity has been reduced; however, data limitations precluded generalizing results from the specific cases analyzed to all sentencing under the guidelines. Similarly, a lack of empirical data on workload prevented a reliable quantification of the impact of the guidelines on the operations of the criminal justice system. Based on the limited statistical data available and interviews with criminal justice system personnel in four districts, the guidelines have apparently increased the workload of judges, prosecutors, probation officers, and defense attorneys. The study concludes that it is impossible to rectify the shortcomings in preguidelines data and develop a more useful baseline for comparing sentencing outcomes before and after the guidelines; consequently, future analytical resources could best be used to evaluate current disparity under the guidelines rather than continuing to focus on comparisons between the preguidelines and current systems. 22 figures and 46 tables