Sacred Heart High School was founded in 1935, graduating its first class in 1939. The gymnasium section of the present building opened in 1959, with the classroom section of the building opening in 1964. Scared Heart High School is operated in conjunction with a seventh and eights grade Junior High School, adjoining a grade school. The campus area for the Sacred Heart School System covers an area of two city blocks in width. It is located just a few minutes fro downtown Miles City.
Sacred Hear High School is a four-year high school, fully accredited by the State of Montana. It maintains membership in both of these professional accrediting agencies as well as in the National Catholic Educational Association.
The daily schedule at Sacred Heart is made up of 30-minute modules. Classes are schedules to meet for one, two, or three mods. There are also four homeroom periods in which attendance is taken, announcements are made, etc. Starting time in the mornings is 8:20 with homeroom, then classes start at 8:30. Lunch is from 12:00 to 12:30. Dismissal is at 3:10. On Friday dismissal is at 2:00. There are also alternative schedules to allow for National School Assemblies, weekly Masses, etc.