To hone in on the complexities of prison downsizing and decarceration it is important to examine the different facets that play a part in these processes. To do so, this volume of The ANNALS brings together an inter-disciplinary group of scholars who research prisons, mass incarceration, and related policies to examine the origins of the prison overcrowding crisis, the diffusion and translation of law and policy reform, the impact of prison downsizing on the criminal justice system, and the future of decarceration.