This is a partial list of agencies under the United States Department of Defense (DoD) which was formerly and shortly known as the National Military Establishment. Its main responsibilities are to control the Armed Forces of the United States. It is headed by the Secretary of Defense.

The department was established in 1947 and is divided into three major Departments—the Department of the Army, Navy and Air Force, as well as a number of other component organizations.

Field activities are DoD agencies which "perform a supply or service activity common to more than one military department".^[1]

• Defense Technical Information Center (DTIC)
• Defense Technology Security Administration (DTSA)
• Department of Defense Education Activity (DOD EA)
• Department of Defense Test Resource Management Center (DOD TRMC)
• Washington Headquarters Services (WHS)
• Office of Local Defense Community Cooperation (OLDCC), formerly Office of Economic

• Defense Advanced Research Projects Agency (DARPA)
• Defense Commissary Agency (DeCA)
• Defense Contract Audit Agency(DCAA)
• Defense Contract Management Agency (DCMA)
• Defense Counterintelligence and Security Agency (DCSA)
• Defense Finance and Accounting Service (DFAS)
• Defense Health Agency (DHA)
• Defense Information Systems Agency (DISA)
• Defense Intelligence Agency (DIA)
• Defense Legal Services Agency (DLSA)
• Defense Logistics Agency (DLA)
• Defense POW/MIA Accounting Agency (DPAA)
• Defense Security Cooperation Agency (DSCA)
• Defense Threat Reduction Agency (DTRA)
• Missile Defense Agency (MDA)
• National Geospatial-Intelligence Agency (NGA)
• National Reconnaissance Office (NRO)
• National Security Agency/Central Security Service (NSA/CSS)
• Pentagon Force Protection Agency (PFPA)

• Armed Services Board of Contract Appeals
• Army and Air Force Exchange Service
• Defense Acquisition University (DAU)
• Defense Criminal Investigative Service (DCIS) (component of DOD Office of Inspector General)
• Joint Personnel Recovery Agency (a Chairman's Controlled Activity)
• Military Postal Service Agency
• National Assessment Group (NAG)
• National Defense University (NDU)
• National Guard Bureau (NGB)
  • Army National Guard (ARNG)
  • Air National Guard (ANG)
• National Intelligence University (NIU) (part of DIA)
• Organization of the Joint Chiefs of Staff (includes NDU)
• Uniformed Services University of the Health Sciences (USUHS)
• United States Court of Appeals for the Armed Forces
• United States Military Entrance Processing Command (USMEPCOM)
• Electromagnetic Spectrum Operations Cross Functional Team (EMSO CFT)
• Close Combat Lethality Task Force (CCLTF)
• Protecting Critical Technology Task Force (PCTTF)

• U.S. Army Criminal Investigation Division (CID)
• U.S. Army Corps of Engineers
• Regional Headquarters
  • Great Lakes Region
  • Missouri River Regional Headquarters (CENWD-MR) (Former Missouri River Division)
  • North Pacific Regional Headquarters (CENWD-NP)(Former North Pacific Division)
• Army Digitization Office (ADO)
• Army Medical Department (AMEDD)
• Army Research Laboratory (ARL)
• Army Review Boards Agency (ARBA)
• U.S. Army Financial Management
• White Sands Missile Range (WSMR)

• Great Lakes and Ohio River Division (CELRD)
• Mississippi Valley Division (CEMVD)
• North Atlantic Division (CENAD)
• Northwestern Division (CENWD)
• Pacific Ocean Division (CEPOD)
• South Atlantic Division (CESAD)
• South Pacific Division (CESPD)
• Southwestern Division (CESWD)

• Cold Regions Research and Engineering Laboratory (CECRL)
• Construction Engineering Research Laboratory (CECER)
• Waterways Experiment Station (CEWES)
• Topographic Engineering Center (CETEC)

Army Commands (MACOMs)

• U.S. Army Forces Command (FORSCOM)
• U.S. Army Futures Command (AFC)
• U.S. Army Materiel Command (AMC)
• U.S. Army Training and Doctrine Command (TRADOC)

• Naval Criminal Investigative Service (NCIS)
• United States Marine Corps Criminal Investigation Division (USMC CID)

• Office of Naval Research (ONR)
• Naval Research Laboratory (NRL)
• Office of Naval Intelligence (ONI)
• United States Naval Academy
• Military Sealift Command (MSC)

• Marine Expeditionary Units
• Commandant of the Marine Corps
• Assistant Commandant of the Marine Corps
• Sergeant Major of the Marine Corps
• Headquarters, United States Marine Corps

• Air Force Research Laboratory
• Air Force Reserve Officer Training Corps (AFROTC)
• Air Force Office of Special Investigations (AFOSI)

Major Commands (MAJCOMs)

• Air Combat Command (ACC)
• Pacific Air Forces (PACAF)
• United States Air Forces in Europe (USAFE)
• Air Force Special Operations Command (AFSOC)
• Air Education and Training Command (AETC)
• Air Mobility Command (AMC)
• Air Force Global Strike Command (AFGSC)
• Air Force Materiel Command (AFMC)
• Air Force Reserve Command (AFRC)

Field Commands

• Space Operations Command (SpOC)
• Space Systems Command (SSC)
• Space Training and Readiness Command (STARCOM)

The United States has eleven Combatant Commands (COCOM); seven Geographical Combatant Commands (GCC) & four Functional Combatant Commands (FCC).

GCCs:

• U.S. Africa Command (USAFRICOM)
• U.S. Central Command (USCENTCOM)
• U.S. European Command (USEUCOM)
• U.S. Indo-Pacific Command (USINDOPACOM)
• U.S. Northern Command (USNORTHCOM)
• U.S. Southern Command (USSOUTHCOM)
• U.S. Space Command (USSPACECOM)

FCCs:

• U.S. Cyber Command (USCYBERCOM)
• U.S. Special Operations Command (USSOCOM)
• U.S. Strategic Command (USSTRATCOM)
• U.S. Transportation Command (USTRANSCOM)

• Combat support agency
• United States Department of Defense
• United States Unified Combatant Commands
• Fourth Estate (Department of Defense)

Most information on this list was taken from Government Information. Some was taken from USA.gov.