Racial disparity in prison and jail populations, measured by the ratio of black to white per capita incarceration rates, varies substantially from state to state. To understand these variations, researchers must examine disparity at earlier stages of the criminal process and also racial differences in socioeconomic status that help explain disparity in cases entering the system. Researchers must adjust disparity ratios to correct for limitations in available data and in studies of prior incarceration rates. Minnesota has one of the highest black/white incarceration ratios. Disparities at the earliest measurable stages of Minnesota's criminal process-arrest and felony conviction-are as great as the disparity in total custody (prison plus jail) populations. Disparities are substantially greater in prison sentences imposed and prison populations than at arrest and conviction. The primary reason is the heavy weight sentencing guidelines give to offenders' prior conviction records. Highly disparate arrest rates appear to reflect unusually high rates of socioeconomic disparity between black and white residents.