The unit was founded in 1920 and has operated continually with a single break from 1945 to 1947 when the Finnish officer training was stopped by order of the Allied Control Commission.

[8][9] Within the Finnish Defence Forces, the vast majority of officers advance through the ranks during their conscription, instead of being commissioned from without for a separate career path.

Those conscript NCOs who are accepted to the National Defence University, are selected on the condition of passing a platoon-leader course that gives the equivalent training as the Reserve Officer School.

Traditionally, the training of a reserve officer has carried certain social distinction and has been tied to high positions in industry and economy.

The high educational level of most reserve officers offers the Finnish Defence Forces a chance to fill many wartime vacancies on the basis of civilian professions.

Typically, they have a civilian occupation or profession that makes them ideal candidates for a wartime position requiring officer training.

[15][16] Such courses are organised annually by the Reserve Officer School, together with the National Defence Training Association of Finland.

During this time, the reservists participate in 40 days of training and exercises in the Reserve Officer School, in addition to a large amount of distance-education.