A regimental combat team (RCT) is a provisional major infantry unit which has seen use by branches of the United States Armed Forces. It is formed by augmenting a regular infantry regiment with smaller combat, combat support and combat service support units.

The United States Army first adopted the RCT concept just prior to World War II, where it served as the infantry-centric counterpart to the Combat Command used by armored forces. RCTs were widely used during World War II and the Korean War but were disbanded after the adoption of the Pentomic structure in 1957.

The United States Marine Corps maintains the use of the RCT to the present day.

In 1939, the US Army formally switched from the square division to the triangular division, eliminating the brigade and leaving the regiment as the basic combat subunit of a division. However, the Army also recognized that it would need a separate infantry force to conduct missions too small for a division and created the regimental combat team (RCT). The 2nd Division, which was first to test the triangular division concept, initially referred to this type of formation as an "echelon" but as the term already had generally accepted military definitions the combat team term was officially adopted instead.

During World War II a typical RCT consisted of an infantry regiment, a field artillery battalion, a combat engineer company, a medical company, and a signals platoon. However the organization could be tailored to fit its mission and might include additional units, such as a company from a separate tank battalion, a company from a tank destroyer battalion, and a battery from an anti-aircraft artillery battalion. Usually the RCT was led by the commanding officer of the infantry regiment (Colonel) but on occasion a brigadier general was sent to command it. Most infantry regiments not part of a division were organized as RCTs, but by the end of the war most infantry divisions were also organizing their regiments as RCTs.

The concept was retained after the end of World War II due to the perceived need for smaller units in the atomic age and RCTs were issued their own shoulder sleeve insignia. RCTs were used extensively during the Korean War, with the 187th Airborne Regimental Combat Team illustrating the typical organization of an RCT from this era. The army also stood up Logistical Commands to support the RCTs of the post-WWII era. The insignia, like the logistical command's were nearly all red, white and blue with simple designs. The RCT was retained until 1957 when the Army was reorganized under the Pentomic structure and adopted the Combat Arms Regimental System (CARS), under which both regiments and battalions were eliminated as tactical units and replaced with battle groups. When the era ended in the early 1970s, so did most of the army logistical commands.

There would be four RCTs that would gain fame:

The U.S. Marine Corps has retained the regiment as a basic unit smaller than a division but larger than a battalion, and it continued to employ reinforced regiments as RCTs in Iraq and Afghanistan.