This article considers how recent correctional reforms in California, which downsized the state prison system, have impacted county jails. Jails have long been overlooked by researchers and, yet, as the state shifts authority for managing certain types of offenders to counties, jails have become an even more important part of the state’s correctional options. Using detailed data from twelve counties, we examine how jails are changing in terms of types of individuals that move through them as well as how long they stay in custody and how they are released. We find that the jail population is increasingly comprised of more serious types of offenders, many of whom are staying in custody for relatively long periods of time. These changes highlight the need for policymakers to consider a variety of options to improve outcomes for offenders when they return to the community as well as the need for additional research to inform to better inform who should be held in custody, what they do while being held, and who might be safely released.