This Special Report presents "data on the use of restrictive housing in U.S. prisons and jails, based on inmate self-reports of time spent in disciplinary or administrative segregation or solitary confinement. The report provides the percentage of prison and jail inmates who were currently held in restrictive housing, those who had spent any time in restrictive housing in the last 12 months or since coming to the facility if shorter, and the total time spent in restrictive housing. It provides prevalence rates for inmates by selected demographic characteristics, criminal justice status and history, current and past mental health status, and indicators of misconduct while in the facility. It also describes the relationship between the use of restrictive housing and facility-level characteristics, including measures of facility disorder and facility composition. Data are from the National Inmate Survey (NIS), 2011-12, conducted in 233 state and federal prisons and 358 local jails, with a sample of 91,177 inmates nationwide. Highlights: Younger inmates, inmates without a high school diploma, and lesbian, gay, and bisexual inmates were more likely to have spent time in restrictive housing than older inmates, inmates with a high school diploma or more, and heterosexual inmates; Inmates held for a violent offense other than a sex offense and inmates with extensive arrest histories or prior incarcerations were more likely to have spent time in restrictive housing than inmates held for other offenses and inmates with no prior arrests or incarcerations; Use of restrictive housing was linked to inmate mental health problems: 29% of prison inmates and 22% of jail inmates with current symptoms of serious psychological distress had spent time in restrictive housing in the past 12 months; More than three-quarters of inmates in prisons and jails who had been written up for assaulting other inmates or facility staff had spent time in restrictive housing in the past 12 months; [and] Among inmates who had spent 30 or more days in restrictive housing in the last 12 months or since coming to the facility, 54% of those in prison and 68% of those in jail had been in a fight or had been written up for assaulting other inmates or staff."