Military Police (MP), an organized body of troops exercising police functions among military personnel. The Military Police Corps of the U.S. Army is headed by a provost marshal general. It maintains law and order, prevents and investigates crime within the army, enforces orders and regulations, and operates stockades. Among its duties are apprehending deserters, guarding military installations, controlling traffic on army posts and in combat zones, and supervising prisoners of war. The MP Corps was created in 1942 and became a permanent branch of the army in 1950.

The U.S. Marine Corps also has Military Police units.