GPA membership is limited to WTO members who have specifically signed or subsequently joined the GPA. WTO members are not required to join the GPA, but the United States urges all WTO members to participate in this important agreement. Several countries, including China, Russia and the Kyrgyz Republic, are negotiating GPA membership. The agreement came into force in 1979 as the Tokyo Round Code on Government Procurement, which came into force in 1981 under the General Agreement on Tariffs and Trade.  It was then renegotiated in parallel with the 1994 Uruguay Round and this version came into force on 1 January 1996. The agreement was then revised on March 30, 2012. The revised MPA came into effect on July 6, 2014.  The GPA`s fundamental objective is to open mutual public procurement between its parties. Following several rounds of negotiations, the GPA parties have opened purchase activities valued at an estimated $1.7 trillion per year for international competition (i.e., suppliers of construction products, services or services). The current signatories to this agreement (april 2014) are: Canada, Chinese Taipei, the European Union – whose member states are Austria, Belgium, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands (including Aruba), Poland, Portugal, Slovakia , Slovenia, Sweden and the United Kingdom – Hong Kong, Iceland, South Korea, Liechtenstein, Singapore, Switzerland and the United States.
Any other WTO member government may accede to this agreement on terms agreed by that government and the current signatories. On March 30, 2012, the parties to the GPA adopted a review of the GPA. The revised agreement expands the markets covered by the GPA to provide U.S. products, services and suppliers with new opportunities to participate in centralized and sub-centralized procurement in other GPA parties. The revised agreement also provides for a substantial improvement in the text of the treaty by modernising the text to take into account current procurement practices and to clarify its commitments.