There are 11 major commands among the tenant units, including: APG is the U.S. Army's oldest active proving ground, established on October 20, 1917, six months after the U.S. entered World War I.

[1][2] The planning and construction were overseen by Brigadier General Colden Ruggles, who later served as the Army's Chief of Ordnance.

A notable scientist was James B. Conant, who helped develop Lewisite at Aberdeen, went on to become the President of Harvard, and oversaw the Manhattan Project for OSRD.

[4] Under the Base Realignment and Closure (BRAC) program, as announced in 2005, the APG is projected to lose the Ordnance School and associated R&D facilities with 3862 military and 290 civilian jobs moving to Fort Gregg-Adams, Virginia.

Although civilian contractors produced the major portion of conventional munitions for World War I, the United States government built federally owned plants on Aberdeen Proving Ground for the manufacture of toxic gas.

Edgewood Arsenal included plants to manufacture mustard gas, chloropicrin and phosgene, and separate facilities to fill artillery shells with these chemicals.

The purpose was to evaluate the impact of low-dose chemical warfare agents on military personnel and to test protective clothing and pharmaceuticals.

Some of the volunteers exhibited symptoms at the time of exposure to these agents but long-term follow-up was not planned as part of the DoD studies.

Simulant agents, incendiaries, decontaminating compounds, signaling and screening smokes, mustard, and herbicides were also released as well as riot control gasses.

[11][12] The U.S. Army Ordnance Corps Museum previously located at APG, was moved to Fort Gregg-Adams, Virginia, as a result of the 2005 Base Realignment and Closure (BRAC) Act.

For statistical purposes the base is delineated as a census-designated place (Aberdeen Proving Ground CDP) by the U.S. Census Bureau.

On-site groundwater sampling has identified perchlorate, various metals, volatile organic compounds (VOCs) and chemical warfare agent degradation products.

People who accidentally ingest or come in direct contact with contaminated groundwater, surface water, soil, or sediments may be at risk.

The U.S. Army brought charges against twelve commissioned and non-commissioned male officers for sexual assault of female trainees under their command.

[20] Following campaigning by PETA, the Physicians Committee for Responsible Medicine and other organizations, the U.S. military announced in 2011 that it was replacing its use of monkeys in the Army's nerve-agent attack training courses with human simulators and other non-animal teaching methods.

[21] A Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System (JLENS) broke free from its mooring station on APG October 28, 2015.