A case file covering 14,393 sentences imposed during 1974-78 was used to compute commitment rates for 18 selected counties and remaining rural areas in the State's eight judicial districts. These rates were then 'corrected' so as to apply to a single body of sentenced offenders with fixed characteristics. This procedure was deemed necessary, since there is substantial variation across Iowa in the types of offenders sentenced, with higher percentages of violent and repeat offenders being in the more populous areas. Sentences to county jails or alternative facilities or probation were not considered incarceration. Disparity was defined as occurring when different sentences were imposed on similar offenders charged with the same or similar offenses. The Sentencing Disparity Study Committee also examined sentencing practices in driving-under-the-influence cases, particulary the use of deferred sentences. Sentence disparity was found to exist in this area as well. Although beyond the committee's assigned task, a number of possible causes of the sentencing disparity found were suggested, including the difference between the actual offense and the offense charged, the public's attitude toward crime, the geographical location of sentencing, prosecutorial practices, police attitudes, caseload variations, and the sentencing judge. A summary is also provided of the findings of recidivism research done by Iowa's Statistical Analysis Center. Tabular data and footnotes are provided.