Leavesden Mental Hospital was founded in 1870 on the outskirts of Abbots Langley by the Metropolitan Asylums Board as the Metropolitan Asylum for Chronic Imbeciles. At the same time the St Pancras Union Workhouse established an Industrial School across the road. In 1920, the asylum was renamed the Leavesden Mental Hospital. The London County Council took control in 1930. In April, 1932, the former St Pancras Industrial School was taken over as an annexe for chronic cases. The hospital closed in 1997.
The Jack the Ripper suspect Aaron Kosminski was admitted to Leavesden Asylum on 19 April 1894. Case notes indicate that Kosminski had been ill since at least 1885. His insanity took the form of auditory hallucinations, a paranoid fear of being fed by other people that drove him to pick up and eat food dropped as litter, and a refusal to wash or bathe.
The hospital had two cemeteries on East Lane. One remains accessible, but the other has been left to become wooded and a condition of the transfer of the land to Three Rivers District Council required it remain in that way.
Since closure in 1997, the hospital has been converted into a private housing estate, Leavesden Court. The development consists mainly of residential apartments, with the charity DEMAND (Design and manufacture for Disability)  operating from the building previously used as the on-site chapel. The workhouse, or south side of the estate, is now the Leavesden Country Park (South) and the Arundel Road housing development.