A simple method of measuring the racial, ethnic, sex, and class composition of jury systems is needed because the representativeness of juries is of fundamental constitutional importance, the degree of representation of major social and demographic groups has only infrequently been measured, and the cost and complexity of the survey technique is prohibitive. By including jury members with many different backgrounds and points of view, the jury is thought to better understand the context and circumstances of specific cases. The initial step in jury selection is the creation of a jury pool or master list of persons eligible for jury selection. This usually involves use of broad-based source lists, such as local voter registration rolls or tax lists. However, the poor and minorities are usually underrepresented on such lists. A systematic examination of the distribution of jurors by neighborhood can reveal the makeup of the jury system for those characteristics that differentiate neighborhoods. This method was employed to examine the jury composition for the 1974-75 judicial biennium for six large urban counties in North Carolina. Findings revealed that blacks and the poor are consistently and substantially underrepresented in both the jury boxes and jury pools in every county, that the primary reason for this is the use of voter registration and personal property tax lists, and that neither list reasonably reflects the community cross-section. Better sources than voter and tax lists must be used, such as telephone directories or lists of licensed drivers. In addition, efforts must be made to reduce the number of excuses and the failure to locate persons selected from the jury pool. Finally, court systems should make public the data on jury makeup for all relevant social and demographic dimensions. Four tables are provided.