United States Deputy Secretary of Defense

Deputy Secretary of Defense of the United States of America
Seal of the Department of Defense
Flag of the Deputy Secretary of Defense
Incumbent Robert O. Work since May 1, 2014
U.S. Department of Defense Office of the Secretary of Defense
Style	Mister Deputy Secretary The Honorable (formal address in writing)
Reports to	Secretary of Defense
Seat	The Pentagon, Arlington County, Virginia, U.S.
Appointer	The President with the advice and consent of the Senate
Term length	No fixed term
Constituting instrument	10 U.S.C. § 132
Inaugural holder	Stephen Early
Formation	1949 see article for further dates
Succession	1st in SecDef succession
Salary	Executive Schedule, Level II
Website	defense.gov

The Deputy Secretary of Defense (acronym: DEPSECDEF) is a statutory office (10 U.S.C. § 132) and the second-highest-ranking official in the Department of Defense of the United States of America.

The Deputy Secretary is the principal civilian deputy to the Secretary of Defense, and is appointed by the President, with the advice and consent of the Senate. The Deputy Secretary, by statute, is designated as the DoD Chief Management Officer and must be a civilian, at least seven years removed from service as a commissioned officer on active-duty at the date of appointment.

The Deputy Secretary of Defense position is currently held by Robert O. Work, a retired Marine colonel who previously served as Under Secretary of the Navy from 2009 to 2013.

Public Law 81-36, 2 April 1949, originally established this position as the Under Secretary of Defense, however Public Law 81-2 16, August 10, 1949, a.k.a. the 1949 Amendments to the National Security Act of 1947, changed the title to Deputy Secretary of Defense. Former Assistant to President Franklin D. Roosevelt, Stephen Early, became the first officer holder when he was sworn-in on May 2, 1949.

Public Law 92-596, October 27, 1972, established a Second Deputy Secretary of Defense position, with both deputies performing duties as prescribed by the Secretary of Defense. The second deputy position was not filled until December 1975. Robert F. Ellsworth, serving from December 23, 1975 until 10 January 1977, was the only one to ever hold that office. Public Law 95-140, 21 October 1977, the law establishing two Under Secretaries of Defense, abolished the second deputy position.