This Article fills that gap. It explores the extent to which voluntary, nonbinding criminal sentencing guidelines influence the sentencing behavior of state trial judges. In particular, it focuses on the ability of such guidelines to encourage judges to sentence consistently and to avoid" impermissibly" taking into account a defendant's race or sex. It also compares such guidelines to the binding guidelines found constitutionally impermissible in Blakely and Booker. In general, the results indicate that voluntary guidelines are able to accomplish much, though not all, that binding guidelines did, especially with respect to sentence variation. For example, voluntary guidelines appear to reduce a measure of variation in sentence length by as much as 35 percent for violent crimes and 21 percent for property crimes. By comparison, the analogous results for binding guidelines are a 57 percent drop for violent crimes and a 54 percent …