The first Superintendent of the hospital, Dr. Phillip Spohn, was also the first Reeve of the Town of Penetanguishene. Most staff members lived on the grounds either in residential sections of the larger buildings or in white clapboard houses, some of which have been preserved as historic sites or active treatment areas. The Superintendent lived in the large Victorian mansion on the edge of the grounds which is now the Georgianwood Addiction Centre. The mansion, also a registered historical site, has the best view of Penetanguishene harbour and was once graced with a lawn tennis court. Dr. Barry Boyd, the last man to call the mansion home, retired as Medical Director in 1978.
All staff now live off the grounds.
In 1933, the first four wards of the Oak Ridge Division were constructed. During this period the name of the entire institution was changed to Ontario Hospital. Prior to 1933, mentally disordered offenders were shunted around the province to locations of convenience. The Oak Ridge Division eventually grew into an active treatment centre which has won world recognition for its research and innovative programs. Since patients rarely moved on in the early days, a second four wards were added to Oak Ridge in the mid-1950's bringing the patient capacity to 300.