The 18th Infantry Regiment ("Vanguards") is an Army Infantry regiment. The 18th Infantry Regiment currently exists with one active battalion under the U.S. Army Regimental System and has no regimental headquarters.1st Battalion, 18th Infantry Regiment's home duty station is located at Fort Riley, Kansas with the 2nd "Dagger" Brigade Combat Team, 1st Infantry Division. It is a combined arms battalion. 2nd Battalion, 18th Infantry Regiment was stationed in Baumholder, Germany as part of the 170th infantry Brigade Combat Team (Separate) and inactivated with the brigade in 2012. 3rd Battalion, 18th Infantry Regiment was stationed in Lawrence, Massachusetts as part of the 187th Infantry Brigade, 94th Army Reserve Command (1963–1994). 4th Battalion, 18th Infantry was part of the Berlin Brigade stationed in West Berlin in the 1960s along with the 2nd and 3rd Battalions, 6th Infantry. West Berlin was 100 miles behind the Iron Curtain in East Germany surrounded by an estimated force of 270,000 Russian and East German troops. The battalion was later reflagged as the 4th Battalion, 6th Infantry.

The United States Army Regimental System (USARS) is an organizational and classification system used by the United States Army. It was established in 1981 to replace the Combat Arms Regimental System (CARS) to provide each soldier with continuous identification with a single regiment, and to increase a soldier's probability of serving recurring assignments with their regiment. The USARS was intended to enhance combat effectiveness by providing the opportunity for a regimental affiliation, thus obtaining some of the benefits of the traditional regimental system.