Background 'Scared Straight' and other similar programs involve organized visits to prison by juvenile delinquents or children at risk for criminal behavior. Programs are designed to deter participants from future offending through firsthand observation of prison life and interaction with adult inmates. These programs remain in use despite research questioning their effectiveness. This is an update of a 2002 review. Objectives To assess the effects of programs comprising organized visits to prisons by juvenile delinquents (officially adjudicated, that is, convicted by a juvenile court) or pre-delinquents (children in trouble but not officially adjudicated as delinquents), aimed at deterring them from delinquency. Search methods To update this review, we searched 22 electronic databases, including CENTRAL, MEDLINE, PsycINFO, and Criminal Justice Abstracts, in December 2011. In addition, we searched clinical trials registries, consulted experts, conducted Google Scholar searches, and followed up on all relevant citations. Selection criteria We included studies that tested programs involving the organized visits of delinquents or children at risk for delinquency to penal institutions such as prisons or reformatives. Studies that had overlapping samples of juvenile and young adults (for example, ages 14 to 20 years) were included. We only considered studies that assigned participants to conditions randomly or quasi-randomly (that is, by odd/even assignment to conditions). Each study had to have a no-treatment control condition and at least one outcome measure of 'post-visit' criminal behavior.