The study sites were chosen because of their diverse sizes, urban-rural and suburban character, volume of arrestees processed, administrative convenience, and quality of local records. Data collected on inmates included background information, current offense, prior record, confinement conditions, disciplinary problems, time and method of release, and disposition. Following an executive summary, the report highlights the enormous differences among the three counties and their jail systems. It then examines how these differences affect the characteristics of persons brought to the jails. The data demonstrate that the overwhelming majority of the jail's business involves persons charged with misdemeanant crimes involving property, drunkenness, and public disorder. They tend to be disproportionately black or Hispanic, male, unemployed or holding a lower class job, and poorly educated compared to the general population. Many are drunk at the time of booking. The report analyzes the nature and extent of pretrial detention across the three jails, noting that the average length of time spent in pretrial detention is small. Most inmates in the sample spent no more than 1 day in jail, and most were released prior to disposition of their charges. Information is also provided on sentenced inmates in jails, with attention to the length of their confinement, disciplinary violations, program participation, security levels, and avenues of release. The sentence length and conditions of confinement varied among the jails. Disciplinary infractions and program participation were rare. Policy implications of these findings are explored with regard to the jail's mission, its role in pretrial detention and sentencing, and its effect as a deterrent. Tables, a description of the methodology, and approximately 50 references are included.