Thinking about imprisonment in a global context not only challenges accepted criminological views of the boundaries of the prison, but raises a series of methodological and intellectual tasks. Critics argue that segregating prisoners according to nationality actually undermines the quality of care and support provided to foreign nationals by preventing full access to the same range of rehabilitation and reintegration initiatives available to citizen prisoners. Foreign national prisoners also encountered additional barriers in maintaining contact with their families, some of whom had uncertain immigration status in the UK, while others had remained in the country of origin. Recent scholarship has improved the importance of nationality in prison by highlighting the interconnections between gender, race and citizenship in shaping prisoners' identities and their experiences of confinement and release. Immigration detention centres differ from prisons in important ways. The spreading of rationales and techniques from penal institutions to immigration detention centres presents particular challenges for individuals who are detained for administrative purposes.