This article, published in the Federal Sentencing Reporter (Vol. 24, No. 1, October 2011) provides a concise overview of the history and current use of segregation (also known as solitary confinement) in the United States, including disciplinary segregation, administrative segregation, protective custody, temporary confinement, and supermax (or closed maximum-security) prisons. In addition to addressing the conditions of confinement in segregation, the authors discuss the ground breaking efforts undertaken by Ohio and Mississippi in the mid 2000s to study and reduce their over-reliance on segregation. The article concludes with a description of Vera’s Segregation Reduction Project which works in partnership with states and local jurisdictions to reduce the use of segregation while ensuring institutional and public safety.