Each jurisdiction should have a Jail Population Management Board, consisting of criminal justice professionals, to direct the data collection/analysis program. The board must analyze its overcrowding problems before any data are collected; for example, the sources of jail bookings, how people are released and the relative incidence of each type of release, how often alternatives to jail commitments are used, etc. The report defines appropriate data elements (i.e., booking number and date, arresting agency, race/ethnicity) and suggests that frequency distributions and two- or three-way cross-tabulations of data elements will suffice for analysis. Planners must consider whether to use manual or computer-based data analysis, find the source documents of data elements, and develop a sampling design and forms. The report recommends that precoded collection forms be used in conjunction with computer-based analysis for large data sets and complex analyses unless short turnaround times are required. Appendixes contain sample program elements and procedures, including a data coding guide, an arrestee flowchart, and a precoded data collection instrument. Tabular data illustrate defendant processing figures derived from the 4-year technical assistance program in data collection provided to 60 jurisdictions in the Law Enforcement Assistance Administration (LEAA)-funded Jail Overcrowding and Pretrial Detainee Program.