This article examines the use of mass incarceration within the United States criminal justice system and explores ways to reduce or scale back its use. For this article, mass incarceration is defined generally as having the following elements: vast numbers of imprisoned citizens and skyrocketing rates of imprisonment, overcrowded facilities, and the concentrated impact on minorities and the poor. The article begins with a discussion of four different forms of legal change that have given rise to mass incarceration: legislative and other statutory changes to the penal code; changes to Federal case law regarding conditions of confinement and related issues; changes to postsentencing law and policy; and the numerous changes to legal practices used in local courtrooms that deal with sentencing and punishment. The author next examines the localized social, cultural, and political factors that have contributed to the rapid growth in mass incarceration. Finally, the author examines potential ways for reducing mass incarceration in local communities. References