English reformatory system designed for youths between 16 and 21, named after an old convict prison at Borstal, Kent. The system was introduced in 1902 but was given its basic form by Sir Alexander Paterson, who became a prison commissioner in 1922. Each institution consists of houses containing, ideally, not more than 50 young offenders, with a housemaster or housemistress and house staff. Training is exacting, based on a full day's hard and interesting work. There are vocational-training courses, with six hours a week of evening education either in the Borstal or in local technical colleges.

The period of training, governed by the progress of the inmate through a grade system, averages about 15 months. On release, the inmate comes under the supervision of the Central Aftercare Association and may be recalled for further training if necessary. Brendan Behan's Borstal Boy (1958) gives a humorous, grim picture of life in a Borstal.