Although research is inconclusive, reports suggest that approximately 80,000–100,000 individuals are housed in isolation at any given time in the United States for 22–24 hr a day. Although this correctional measure is commonly reserved for inmates deemed the worst of the worst, findings reveal that inmates who are male, economically disadvantaged, and racial or ethnic minorities are disproportionately placed in solitary confinement. Further, it is necessary to acknowledge the harmful impact that segregation has on youth who are still developing physically, cognitively, and socially. Of particular concern is the fact that over a century of research indicates that the conditions of confinement exacerbate psychiatric disorders among inmates. Thus, given the exceptional risk associated with its use for this vulnerable prison population, this entry focuses on ...