Intended to be accessible to everyone, the Disparity Index Computation Database affords users the ability to assess the level of racial/ethnic disparity at various stages of the criminal justice process. The database can be used to determine whether a disparity exists and help determine where in the criminal justice process the disparity is being introduced. This manual was developed, with support from the U.S. Department of Justice, Office of Juvenile Justice and Delinquency Prevention to assist those wanting to assess disproportionate minority representation (DMR) utilizing the Disparity Index Computation Database. The manual provides comprehensive coverage of many, if not all aspects in using the database, including: a flow chart of Illinois’ juvenile justice system process, decisions on tracking and variables to use, grid points, variables, reports, using the database, identifying the variables by which disparity will be identified, entering grid points and connections, entering variables and values for variables, combining variables, and building a dataset. The manual concludes with an explanation on creating and generating reports from the data. Figures