Summary: Data limitations make it impossible to know how effective the federal sentencing guidelines mandated in 1987 have been in reducing racial and other disparities in the sentences given to similar offenders for similar crimes. Until the 1980s, judges had wide discretion in meting out prison sentences, resulting in vastly different sentences for individuals convicted of similar crimes. Some studies suggested that the judge hearing a case was a better indicator of a likely prison term than either the crime or the defendant. The Sentencing Reform Act of 1984 brought sweeping changes to federal sentencing policy, requiring the development of sentencing guidelines, eliminating parole, and scrapping rehabilitation as a goal of imprisonment. GAO and the U.S. Sentencing Commission evaluated the impact of the guidelines but, because of a lack of data, could not determine definitively how effective they had been in reducing sentencing disparity. The work load of the criminal justice system, however, appears to be increasing as a result of the guidelines. GAO recommends that the Commission continue to collect data and do the analyses needed to determine whether sentencing disparity is increasing, decreasing, or remaining stable under the guidelines and the amount of disparity that is unwarranted. The Commission should also continue to explore the impact of the guidelines on the operations of the criminal justice system.