It was founded in 1975 in response to the Indian nuclear test of the previous year. The test demonstrated that certain non-weapons specific nuclear technology could be readily turned to weapons development. Nations already signatories of the NPT saw the need to further limit the export of nuclear equipment, materials or technology. Another benefit was that non-NPT and non-Zangger Committee nations, then specifically France, could be brought in.
A series of meeting in London from 1975 to 1978 resulted in agreements on the guidelines for export, these were published as INFCIRC/254 (essentially the Zangger "Trigger List") by the IAEA. Listed items could only be exported to non-nuclear states if certain IAEA safeguards were agreed to or if exceptional circumstances relating to safety existed.
Because of the series of meetings in London, in the past the NSG was referred to as the London Group or Club, or the London Suppliers Group.
The NSG did not meet again until 1991. The "Trigger List" remained unchanged until 1991, although the Zangger list was regularly updated. The revelations about the Iraqi weapons program following the first Gulf War led to a tightening of the export of so-called dual-use equipment. At the first meeting since 1978, held at the Hague in March 1991, the twenty-six members agreed to the changes, which were published as the "Dual-use List" in 1992, and also to the extension of the original list to more closely match the up-to-date Zangger list. A regular series of plenary meetings was also arranged as was the regular updating of the two key lists.
Initially the NSG had seven members, Canada, the Federal Republic of Germany, France, Japan, USSR, United Kingdom, and United States. In 1976-77 membership was expanded to fifteen with the admittance of Belgium, Czechoslovakia, the German Democratic Republic, Italy, the Netherlands, Poland, Sweden, and Switzerland. Twelve more nations joined up to 1990. Following the collapse of the Soviet Union a number of former republics have been given observer status as a stage towards future membership.
As of 2002 the NSG has 39 members: Argentina, Australia, Austria, Belgium, Belarus, Brazil, Bulgaria, Canada, Cyprus, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Japan, Latvia, Luxembourg, Netherlands, New Zealand, Norway, Poland, Portugal, Romania, Russia, Slovakia, Slovenia, South Africa, South Korea, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom, and United States.