ASEAN was founded by five states, mostly from maritime Southeast Asia: the Philippines, Indonesia, Malaysia, Singapore, and Thailand. The British protectorate of Brunei joined six days after the country became independent from the United Kingdom on January 8, 1984. The mainland states of Vietnam, Laos, and Myanmar were later admitted. Vietnam joined on July 28, 1995, while Laos and Myanmar were admitted on July 23, 1997. Cambodia became the newest member when it was admitted on April 30, 1999.
The Melanesian state of Papua New Guinea has had observer status since 1976. In July 23, 2006, José Ramos Horta, Prime Minister of Timor-Leste, signed a formal request for membership and expected the accession process to last at least five years before the then-observer state became a full member. Australia is also interested in becoming a member, although this is opposed by some members.
In the 1970s, the organisation embarked on a program of economic cooperation, following the Bali Summit of 1976. This floundered in the mid-1980s and was only revived around 1991 due to a Thai proposal for a regional free trade area. The bloc then grew when Brunei Darussalam became the sixth member after it joined on January 8, 1984, barely a week after the country became independent on January 1.
During the 1990s, the bloc experienced an increase in both membership as well as in the drive for further integration. In 1990, Malaysia proposed the creation of an East Asia Economic Caucus composing the then-members of ASEAN as well as the People's Republic of China, Japan, and South Korea, with the intention of counterbalancing the growing influence of the United States in the APEC as well as in the Asian region as a whole. This proposal, however, failed since it faced heavy opposition from Japan and the United States.
Despite this failure, member states continued to work for further integration. In 1992, the Common Effective Preferential Tariff (CEPT) scheme was signed as a schedule for phasing tarrifs and as a goal to increase the region’s competitive advantage as a production base geared for the world market. This law would act as the framework for the ASEAN Free Trade Area.
On July 28, 1995, Vietnam became the seventh member, Laos and Myanmar joined two years later in July 23, 1997. Cambodia was to have joined together with Laos and Myanmar, but was deferred due to the country's internal political struggle. The country later joined on April 30, 1999, following the stabilization of its government. This allowed the bloc to include all countries within Southeast Asia.
At the turn of the 21st century, issues shifted to involve a more environmental prospective. The organization started to discuss environmental agreements. These included the signing of the ASEAN Agreement on Transboundary Haze Pollution in 2002 as an attempt to control haze pollution in Southeast Asia. Unfortunately, this was unsuccessful due to the outbreaks of the 2005 Malaysian haze and the 2006 Southeast Asian haze. Other environmental treaties introduced by the organization include the Cebu Declaration on East Asian Energy Security and the Asia-Pacific Partnership on Clean Development and Climate, both of which are responses to Global Warming and the negative effects of fossil fuel.
Through the Bali Concord 11 in 2003, ASEAN has subscribed to the notion of democratic peace, which means all member countries believe democratic processes will promote regional peace and stability. Also the non-democratic members all agreed that it was something all member states should aspire to.
The leaders of each country, particularly Mahatir Mohammad of Malaysia, also felt the need to further integrate the region. Beginning in 1997, the bloc began creating organizations within its framework with the intention of achieving this goal. ASEAN Plus Three was the first of these and was created to improve existing ties with the People's Republic of China, Japan, and South Korea. This was followed by the even larger East Asia Summit, which included these countries as well as India, Australia, and New Zealand. This new grouping acted as a prerequisite for the planned East Asia Community, which was supposedly patterned after the now-defunct European Community. The ASEAN Eminent Persons Group was created to study the possible successes and failures of this policy as well as the possibility of drafting an ASEAN Charter.
In 2006, ASEAN was given observer status at the United Nations General Assembly. As a response, the organization awarded the status of "dialogue partner" to the United Nations.
In 2007, ASEAN will be celebrating her 40th anniversary.