The original member states of the World Trade Organization are the parties to the GATT after ratifying the Uruguay Round Agreements, and the European Communities. They obtained this status at the entry into force on 1 January 1995 or upon their date of ratification. All other members have joined the organization as a result of negotiation, and membership consists of a balance of rights and obligations. The process of becoming a World Trade Organization (WTO) member is unique to each applicant country, and the terms of accession are dependent upon the country's stage of economic development and the current trade regime.
As is typical of WTO procedures, an offer of accession is only given once consensus is reached among interested parties. The process takes about five years, on average, but it can take some countries almost a decade if the country is less than fully committed to the process, or if political issues interfere. The shortest accession negotiation was that of Kyrgyzstan, lasting 2 years and 10 months. The longest were that of Russia, lasting 19 years and 2 months, Vanuatu, lasting 17 years and 1 month, and China, lasting 15 years and 5 months.
As of 2007, WTO member states represented 96.4% of global trade and 96.7% of global GDP.Iran, followed by Algeria, are the economies with the largest GDP and trade outside the WTO, using 2005 data.
The process of accession can be broken down into four major stages: a country wishing to accede to the WTO submits an application to the General Council. The government applying for membership has to describe all aspects of its trade and economic policies that have a bearing on WTO agreements. The application is submitted to the WTO in a memorandum which is examined by a working party open to all interested WTO Members, and dealing with the country's application. For large countries such as Russia, numerous countries participate in this process. For smaller countries, the Quadrilateral group of countries – consisting of the EU, the United States, Canada and Japan – and an applicant's neighboring countries are typically most involved. The applicant then presents a detailed memorandum to the Working Party on its foreign trade regime, describing, among other things, its economy, economic policies, domestic and international trade regulations, and intellectual property policies. The Working Party Members submit written questions to the applicant to clarify aspects of its foreign trade regime with particular attention being paid to the degree of privatization in the economy and the extent to which government regulation is transparent. After all necessary background information has been acquired, the Working Party will begin meeting to focus on issues of discrepancy between the WTO rules and the Applicant's international and domestic trade policies and laws. The WP determines the terms and conditions of entry into the WTO for the applicant nation, and may consider transitional periods to allow countries some leeway in complying with the WTO rules.