The 1st Marine Regiment is an infantry regiment of the United States Marine Corps based at Marine Corps Base Camp Pendleton, California. The regiment is under the command of the 1st Marine Division and the I Marine Expeditionary Force. The 1st Marine Regiment is also sometimes referred to as "Regimental Combat Team 1" or "Inchon".

Marine Corps Base Camp Pendleton is the major West Coast base of the United States Marine Corps and is one of the largest Marine Corps bases in the United States. It is on the Southern California coast in San Diego County and is bordered by Oceanside to the south, San Clemente and Orange County to the north, Riverside County to the northeast, and Fallbrook to the east.