Summarizes the technical work underlying the conclusions of the Interagency Working Group on Federal Criminal Case Processing Statistics. The Working Group, convened in 1995, was tasked by the Attorney General to study, identify, and reconcile differences in official statistics describing the Federal criminal justice system reported by the Administrative Office of the U.S. Courts, the Executive Office for U.S. Attorneys, the U.S. Sentencing Commission, the Federal Bureau of Prisons, and the Bureau of Justice Statistics. The Working Group concluded that the differences in official statistics are attributable to (1) the differing ways the agencies define defendants in key case processing events, (2) the time periods covering the reported events, (3) the methods used to classify offenses and case types, and (4) the methods used to classify disposition and sentences imposed.