Capreol developed its first high school in 1923 in R.J. Gignac's store on Kelly Street. The school, named Continuation School, was taught by Fern McGonegal and consisted of thirteen students attending grades 9 through 11.
One year after its opening, in 1924, the Capreol School Board asked the Town Council for twelve acres of unsurveyed land to use in the building of a future high school. The School Board was awarded the land on the south side of Meehan Street and plans were immediately started to build a high school.
Capreol High School was completed in November of 1926 and was officially opened by the Honourable Charles McCrae.
By August of 1935, the Department of Education changed the school's status to that of a full high school. This meant that the students could receive all five grades of high school in Capreol.
With the coming of World War II, many young men were trading school books for rifles as they enlisted in the armed forces. This was an especially difficult time for both students and teachers as they were left hoping for their classmates' safe return.
In the 1940's, the school received a new crest and motto thanks to then principal, Leonard A. Gilbert. The new motto of the school became "Sub Septentrionibus Lucerna" or "A Light Below the Seven Stars" (in reference to the Big Dipper).
Over the years, class sizes began to increase and eventually, in the 1950's, additional classes were being held in the basement of the school to accommodate all of the students. The lack of adequate classroom space became a concern to the town and eventually, the Department of Education ordered that four additional classrooms be added to the school. In 1950, a new Commercial Department was implemented in the school.