The Defense Distinguished Service Medal is a United States military award which is presented for exceptionally distinguished performance of duty contributing to national security or defense of the United States. The decoration is awarded only at the highest levels of the military while assigned to a joint activity. The DDSM may also be awarded to other senior officers whose direct and individual contributions to national security or defense are recognized as being so exceptional in scope and value as to be equivalent to contributions normally associated with positions encompassing broader responsibilities.

It is the United States's highest peacetime defense award. Normally, such responsibilities deserving of the Defense Distinguished Service Medal are held by the most senior officers such as the Chairman and Vice Chairman of the Joint Chiefs of Staff, the Chiefs and Vice Chiefs of the Services, and Commanders and Deputy Commanders of the Unified Commands whose duties bring them into direct contact with the Secretary of Defense and other senior officials.

The medal is gold in color and on the obverse it features a medium blue enameled pentagon (point up). Superimposed on this is an American bald eagle with wings outspread facing left grasping three crossed arrows in its talons and on its breast is a shield of the United States. The pentagon and eagle are enclosed within a gold pieced circle consisting, in the upper half of thirteen five-pointed stars and in the lower half, a wreath of laurel on the left and olive on the right. At the top is a suspender of five graduated gold rays. The reverse of the medal has the inscription "For Distinguished Service" at the top in raised letters, and within the pentagon the inscription "From The Secretary of Defense To," all in raised letters. This decoration takes precedence over the Distinguished Service Medals of the separate services and is not to be awarded to any individual for a period of service for which an Army, Navy, Air Force or Coast Guard Distinguished Service Medal is awarded.