The Marine Corps Expeditionary Medal is a decoration of the United States Marine Corps which was first created on 8 May 1919. Originally known as the Marine Corps Expeditionary Ribbon, a full-sized medal was authorized in July 1921 by Presidential Order of Warren G. Harding. The Marine Corps Expeditionary Medal is therefore one of the oldest decorations of the United States military which is still issued to active duty personnel.

To be awarded the Marine Corps Expeditionary Medal, personnel must have engaged in a landing on foreign territory, participated in combat operations against an opposing force, or must have participated in a designated operation for which no other service medal is authorized. After 1961, some commands permitted eligible personnel to choose between the Marine Corps Expeditionary Medal, or the Armed Forces Expeditionary Medal, depending on the nature of the operation in question.