Between 1975 and 2007, the American incarceration rate increased nearly fivefold, a historic increase that puts the United States in a league of its own among advanced economies. We incarcerate more people today than we ever have, and we stand out as the nation that most frequently uses incarceration to punish those who break the law. What factors explain the dramatic rise in incarceration rates in such a short period of time? In Why Are So Many Americans in Prison? Steven Raphael and Michael A. Stoll analyze the shocking expansion of America’s prison system and illustrate the pressing need to rethink mass incarceration in this country.