(kadetskii korpus), in Russia, secondary military educational institutions restricted to children of the privileged classes. They originated in the second half of the 17th century, when cadet schools were set up in Prussia to prepare children of the nobility for military service.

In Russia the first cadet corps was founded in 1732 in St. Petersburg under the name Korpus Kadet, or Corps of Cadets. (After 1752, when the Naval Cadet Corps was founded, it was renamed the Land Forces Gentry Cadet Corps and later, the First Cadet Corps.) In setting up cadet corps the government of Anna Ivanovna appeased the nobility, who demanded among other privileges the right to serve in the army only as officers. But in the 18th century the cadet corps trained not only officers but also civilian officials, diplomats, judges, and others. In the first half of the 19th century they became strictly military educational institutions, in which students received general as well as specialized military education.

In 1863 the cadet corps were transformed into military Gymnasiums and became general educational institutions but retained the military uniform and a semimilitary regime. In 1882 these Gymnasiums were again reorganized into cadet corps, although the program of general educational instruction was essentially maintained. This reform amounted to a greater militarization; civilian teachers were replaced by officers, and military discipline was strengthened. As for military organization the cadet corps were divided into companies and the companies, into detachments. In the postreform period some cadet corps admitted children who were not of gentry origin, but children of the nobility, primarily of officers, remained in the majority.

The curriculum and the program changed many times throughout the history of the cadet corps. After 1900, when Prince Konstantin Konstantinovich was in charge of military education, the program was greatly expanded. Chemistry, mechanics, and some higher mathematics were added to the curriculum, and the number of class hours of natural history and physics were increased. Thus, the program of the cadet corps corresponded more or less to the curriculum of the Realschulen.

The cadet corps were administered by the Main Directorate of Military Educational Institutions. By 1917 there were 29 cadet corps in the Russian Empire (not counting the Naval Corps and the Corps of Pages, with a total of over 10, 000 cadets). After the February Revolution of 1917 the cadet corps were renamed Gymnasiums of the military departments, but the program of instruction did not change at all. In 1918 the cadet corps were closed because of the liquidation of the old army.