Examines patterns of federal sentencing disparity among white and black offenders, by sentence received, and looks at judicial variation in sentencing since Booker v. United States, regardless of race. It summarizes U.S. Sentencing Guidelines, discusses how approaches of other researchers to the study of sentencing practices differ from this approach, defines disparity as used in this study, and explains the methodology. This working paper was prepared by Abt Associates for BJS in response to a request by the Department of Justice's Racial Disparities Working Group to design a study of federal sentencing disparity. Data are from BJS's Federal Justice Statistics Program, which annually collects federal criminal justice processing data from various federal agencies. The analysis uses data mainly from the U.S. Sentencing Commission.