Saint Dympna Hospital first opened its doors in 1832 under the direction of Dr. Neal Kirkpatrick. At that time, the hospital consisted of only three rooms, four beds, and a small volunteer staff of local nuns. Dr. Kirkpatrick dedicated his life to serving the mentally ill and creating a facility at St. Dympna that would serve as a model for future hospitals opening throughout the state. Nestled in the hills twenty miles away from the nearest town, the hospital has grown into a unique oasis for the advancement of mental health.

Today, Saint Dympna Hospital for the Criminally Insane is classified as a moderate to medium security facility and has a bed capacity to treat up to 946 individuals. Patients are admitted to the hospital based upon criminal convictions in conjunction with assessments from state certified mental health officials.

Saint Dympna's operating costs are funded by the Department of Mental Health, the State Corrections Council, various public grants, and a private endowment. The hospital's programs meet national standards set by the Joint Commission, certification from the Centers for Medicare & Medicaid Services, and license from the Department of Health Services. The hospital is under the administration of the Director of the Department of Mental Health.