The preliminary findings of a study conducted by the Vera Institute of Justice, with funding from the National Institute of Justice, are presented by Don Steman and Andreas Rengifo. The main research questions focused on how State sentencing and corrections policies vary across States over time; the variables associated with the growth of State incarceration rates; and the impact of policies on the size and variation of State incarceration rates. The analysis explored every State sentencing and corrections policy for every State for each year between 1975 and 2002. Policies under analysis included indeterminate and determinate sentencing, probation and non-prison sanctions, structured sentencing, time served requirements, sentencing enhancements for drug offenses, habitual offender laws, mandatory sentencing laws, sentence reduction credits, and post-release supervision. Results of statistical analyses revealed several social, economic, political, and systemic variables that were related to the growth of State incarceration rates; these included high violent crime rates, large minority populations, lower incomes, Republic Governor, religious conservatism, and higher rates of drug arrests. In terms of the impact of specific sentencing policies, results indicated that determinate sentencing, presumptive sentencing, and voluntary sentencing guidelines alone were not associated with incarceration rates. However, the interaction of these policies does impact incarceration rates within a State: States with determinate sentencing and presumptive sentencing guidelines have lower incarceration rates while States with determinate sentencing and voluntary sentencing guidelines have higher incarceration rates. Directions for future research are identified and include the analysis of how sentencing policies impact communities as well as different parts of the criminal justice system. The findings suggest to policymakers that specific combinations of policies may be more important than individual policies in terms of impacting the State incarceration rate. A question and answer session follows the main presentation.