In the United States, jails confine large numbers of people each day and process nearly 12 million admissions each year. The estimated average daily population in American jails, as of midyear 2014, was 744,600. Jail overcrowding has continued to remain a problem at the onset of the new millennium, especially in large jurisdictions. More stringent drug and crime control policies and enforcement strategies led to the precipitous rise in the jail population. Jails are a critical resource for the criminal justice system and the larger community. As local institutions, jails often serve the medical and behavioral healthcare needs of the residents in a jurisdiction and are home to the most impoverished and disenfranchised members of the community: the unemployed, the homeless, and those with addiction, and mental illness. Jails have also become increasingly more populated by women. This special issue of The Prison Journal was compiled to focus further attention on servicing and managing the jail detainee population and provides an in-depth look at jails through a variety of lenses. The issue includes articles about the proper role of the jail as a venue for delivering behavioral healthcare and other services and the jail reentry process in rural jurisdictions. Other articles explore a jail reentry program for detainees with substance use disorders; the problems and challenges of female detainees; the nature and extent of trauma among women in a large urban jail; the use and abuse of solitary confinement in jails; and the mentally ill in jails.