The U.S. Sentencing Guidelines are among the most ambitious attempts in history to control sentencing discretion. However, a major sea change occurred in January of 2005, when the U.S. Supreme Court ruled in United States v. Booker and Fanfan, that in order to be constitutional, the Federal guidelines must be advisory rather than presumptive. The impact of the Booker/Fanfan decisions on interjurisdictional variation and sentencing disparity is an opportunity to examine the issue of whether the increased opportunity to sentence according to substantively rational criteria entails increased extralegal disparity. The study drew on a conceptualization of courts as communities and a focal concerns model of sentencing decisions to frame expectations about Federal sentencing in the wake of Booker/Fanfan. The authors test these expectations using USSC data on Federal sentencing outcomes from four time periods: prior to the 2003 PROTECT Act, the period governed by the PROTECT Act, post-Booker/Fanfan, and post-Gall v US. In general, the authors found that extralegal disparity and between-district variation in the effects of extralegal factors on sentencing have not increased post-Booker and Gall. The authors conclude that allowing judges greater freedom to exercise substantive rationality does not necessarily result in increased extralegal disparity. (Published Abstract)