The era of mass incarceration, which made the United States the world’s leading jailer, appears to be coming to an end. What is likely to follow is an era of decarceration, aimed at reducing the incarcerated population. In this working paper, we discuss the problems associated with mass incarceration and the current climate that is likely to make decarceration a reality. We discuss the importance of developing a “smart decarceration” approach—one that is effective, sustainable, and socially just. We then articulate interrelated goals for the era of decarceration, and offer guiding concepts that will help to meet these goals through transformation of the criminal justice system.