The first reached fruition when President Harry Truman signed the National Security Acts of 1947 and 1949, creating the Department of Defense.

[3]) To give the nascent Office of the Secretary of Defense (OSD) the technical expertise and analytic resources to hold its own and to help make unification a reality, James Forrestal, the department's first secretary, established the Weapons Systems Evaluation Group (WSEG)[4] in 1948 to assist OSD and the Organization of the Joint Chiefs of Staff by: The demands on WSEG were more than its small staff of military and civilian analysts could satisfy, and by the early years of the Dwight Eisenhower administration, there were calls for change.

[citation needed] The several options gradually coalesced into one and, in 1955, the Secretary of Defense and the Chairman of the Joint Chiefs of Staff asked James R. Killian, Jr., then president of MIT, to help form a civilian, nonprofit research institute.

The Institute would operate under the auspices of a university consortium to attract highly qualified scientists to assist WSEG in addressing the nation's most challenging security problems.

Shortly after its creation, the mandate of this division was broadened to include scientific and technical studies for all offices of the Director of Defense, Research and Engineering (DDR&E).

[6] Universities overseeing IDA expanded from the five initial members in 1956 — Caltech, Case Western Reserve, MIT, Stanford and Tulane — to twelve by 1964 with the addition of California, Chicago, Columbia, Illinois, Michigan, Pennsylvania, and Princeton.

[9] IDA's support of the National Security Agency began at its request in 1959, when it established the Center for Communications Research in Princeton, New Jersey.

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